Capacitive sensor device

ABSTRACT

A capacitive sensor device comprises a first sensor electrode, a second sensor electrode, and a processing system coupled to the first sensor electrode and the second sensor electrode. The processing system is configured to acquire a first capacitive measurement by emitting and receiving a first electrical signal with the first sensor electrode. The processing system is configured to acquire a second capacitive measurement by emitting and receiving a second electrical signal, wherein one of the first and second sensor electrodes performs the emitting and the other of the first and second sensor electrodes performs the receiving, and wherein the first and second capacitive measurements are non-degenerate. The processing system is configured to determine positional information using the first and second capacitive measurements.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims benefit under 35 U.S.C. § 119(e) of U.S.Provisional Application No. 61/177,897, filed on May 13, 2009, andentitled, “CAPACITIVE SENSOR DEVICE”, and U.S. Provisional ApplicationNo. 61/224,814, filed on Jul. 10, 2009, and entitled “ABSOLUTECAPACITANCE SENSING ON A TRANS-CAPACITANCE IMAGER.” U.S. ProvisionalApplication No. 61/177,897 is incorporated herein by reference. Thepresent application is a continuation application of U.S. patentapplication Ser. No. 12/778,940, filed May 12, 2010, that issued as U.S.Pat. No. 9,804,213 on Oct. 31, 2017, and entitled “CAPACITIVE SENSORDEVICE.” Thus, the present application claims benefit of U.S. patentapplication Ser. No. 12/778,940 under 35 U.S.C. § 120. U.S. patentapplication Ser. No. 12/778,940 is hereby incorporated in its entirety.U.S. patent application Ser. No. 12/778,940 claims benefit under 35U.S.C. § 119(e) of U.S. Provisional Patent Application No. 61/177,897,filed on May 13, 2009, and U.S. Provisional Patent Application No.61/224,814, filed on Jul. 10, 2009.

BACKGROUND

Capacitive sensing devices are widely used in modern electronic devices.For example, capacitive sensing devices have been employed in music andother media players, cell phones and other communications devices,remote controls, personal digital assistants (PDAs), and the like. Thesecapacitive sensing devices are often used for touch based navigation,selection, or other functions. These functions can be in response to oneor more fingers, styli, other objects, or combination thereof providinginput in the sensing regions of respective capacitive sensing devices.However, there exist many limitations to the current state of technologywith respect to capacitive sensing devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the technology for acapacitive sensor device and, together with the description, serve toexplain principles discussed below. The drawings referred to in thisbrief description should not be understood as being drawn to scaleunless specifically noted.

FIG. 1 is a plan view block diagram of an example capacitive sensordevice that can be implemented to include one or more embodiments of theinvention.

FIG. 2 shows an example of an external object drawing away part of anelectric field that would otherwise have coupled the transmitter andreceiver sensor electrodes.

FIG. 3 shows a simplified model of a sensor with two sensor electrodesand one external object, in accordance with embodiments of the presenttechnology.

FIG. 4 shows several non-limiting modulation examples, in accordancewith embodiments of the present technology

FIGS. 5A and 5B show a top view and a side view, respectively, of anexample sensor electrode pattern, in accordance with embodiments of thepresent technology.

FIGS. 6A, 6B and 6C show a top view of example sensor electrodepatterns, in accordance with embodiments of the present technology.

FIG. 7 shows a combination of an absolute capacitance sensor and atranscapacitive image sensor, in accordance with embodiments of thepresent technology.

FIG. 8 is a block diagram of an example capacitive sensor device, inaccordance with embodiments of the present technology.

FIG. 9 is flowchart of an example method of determining positionalinformation using a capacitive sensor device comprising a first sensorelectrode and a second sensor electrode, in accordance with embodimentsof the present technology.

FIG. 10 is a block diagram of an example capacitive sensor device, inaccordance with embodiments of the present technology.

FIG. 11 is flowchart of an example method of sensing using a capacitivesensor device comprising a first plurality of sensor electrodes alignedalong a first axis and a second plurality of sensor electrodes alignedalong a second axis non-parallel to the first axis, in accordance withembodiments of the present technology.

FIG. 12 shows potential ambiguity with profile-based position sensingmethod of disambiguating the configuration using transcapacitancesensing.

FIG. 13 is a block diagram of an example capacitive sensor device, inaccordance with embodiments of the present technology.

FIG. 14 is flowchart of an example method of sensing using a capacitivesensor device comprising a first plurality of sensor electrodes alignedalong a first axis and a second plurality of sensor electrodes alignedalong a second axis non-parallel to the first axis, in accordance withembodiments of the present technology.

FIG. 15 is a block diagram of an example capacitive sensor device, inaccordance with embodiments of the present technology.

FIG. 16 is flowchart of an example method of sensing using a capacitivesensor device comprising a first plurality of sensor electrodes alignedalong a first axis and a second plurality of sensor electrodes alignedalong a second axis non-parallel to the first axis, in accordance withembodiments of the present technology.

FIGS. 17A, 17B, 18A, 18B, 19A, 19B, 20A and 20B show embodiments of thepresent technology that are capable of measuring both absolute andtrans-capacitance to resolve two regions, in accordance with the presenttechnology.

FIG. 21 shows a conceptual diagram for a transcapacitive imageintegrated circuit in accordance with embodiments of the presenttechnology.

FIG. 22 shows a conceptual diagram for an absolute image integratedcircuit, in accordance with embodiments of the present technology.

FIG. 23 is a block diagram of an example capacitive sensor device, inaccordance with embodiments of the present technology.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments of the presenttechnology, examples of which are illustrated in the accompanyingdrawings. While the present technology will be described in conjunctionwith embodiments, it will be understood that the descriptions are notintended to limit the present technology to these embodiments. On thecontrary, the descriptions are intended to cover alternatives,modifications and equivalents, which may be included within the spiritand scope as defined by the appended claims. Furthermore, in thefollowing detailed description, numerous specific details are set forthin order to provide a thorough understanding of embodiments of thepresent technology. However, one of ordinary skill in the art willunderstand that embodiments of the present technology may be practicedwithout these specific details. In other instances, well known methods,procedures, components, and circuits have not been described in detailas not to unnecessarily obscure aspects of the present technology.

Overview of Discussion

The discussion will begin with description of an example capacitivesensor device with which or upon which various embodiments describedherein may be implemented. The discussion will then turn to anexplanation of the terminology associated with the capacitive sensordevice in accordance with embodiments of the present technology.Discussions of grounding, noise, and types of capacitance will bepresented. A discussion of example capacitive sensor electrodes andsensor arrays will be presented; the discussion will include descriptionof some techniques and situations for performing both absolute andtranscapacitive sensing with the same sensor device and fordisambiguation through transcapacitive sensing. The discussion will thenbe followed by a detailed description focusing on aspects of thestructure of various example capacitive sensing devices and variousexample conceptual and circuit diagrams that are discussed with a viewtoward use and operation of embodiments described herein.

Some capacitive sensing devices may be configured to acquire electretunmodulated capacitive measurements (may be referred to as electretsensing or sensors). However, these measurements are typically not usedby touch input devices for sensing touch input. Electret sensingrequires a difference in voltage (or a trapped charge) which can inducecurrents (or charge) as the object moves toward the sensor. Because thevoltage is difficult to control on an external object, this method isnot typically used. Also, since electret capacitive measurements arefundamentally DC they can not be demodulated and made narrow bandsensors. Electret capacitive measurements are not performed by theembodiments described herein

Example Capacitive Sensing Device

FIG. 1 is a plan view block diagram of an example capacitive sensordevice 100 that can be implemented to include one or more embodiments ofthe present invention. As illustrated, capacitive sensor device 100includes a sensor 108 that is disposed on a substrate 102. Sensor 108includes two pluralities of sensor electrodes 120, 130. Although onlytwo sensor electrodes are illustrated in each plurality (120, 130), itis appreciated that either or both can include more than two sensorelectrodes. Although not illustrated, in some embodiments there may beonly a single sensor electrode 120-1 and a plurality of sensorelectrodes 130-1 to 130-n, or plurality of sensor electrodes 120-1 to120-n and a single sensor electrode 130-1. Likewise, while notillustrated, in some embodiments, there may be only a single sensorelectrode 120-1 and a single sensor electrode 130-1. It is alsoappreciated that sensor electrodes 120 and sensor electrodes 130 areseparated by a dielectric layer (not shown). In some embodiments,plurality of sensor electrodes 120 and plurality of sensor electrodes130 may be disposed on separate substrates and the substrates may bejoined together before operation.

As illustrated, sensor electrodes 120, 130 are coupled to processingsystem 110 by conductive routing traces 104, 106. For ease ofillustration and description, sensor 108 is shown with sensor electrodes120, 130 arranged in an x/y grid, which creates capacitive pixels wherecapacitive coupling is measured between sensor intersections. It isappreciated, that the discussion herein is not limited to such anarrangement of sensor 108, but is instead applicable to numerous sensorelectrode patterns, some of which are illustrated herein by way ofexample and not of limitation.

Capacitive sensor device 100 can be utilized to communicate user input(e.g., using a user's finger, a probe such as a stylus, and/or someother external input object) to a computing device or other electronicdevice. For example, capacitive sensor device 100 can be implemented asa capacitive touch screen device that can, in some embodiments, beplaced over an underlying image or an information display device (notshown). In this manner, a user would view the underlying image orinformation display by looking through the substantially transparentsensor electrodes (not illustrated) in sensor 108 of capacitive sensordevice 100 as shown. It is noted that one or more embodiments, inaccordance with the present invention, can be incorporated with acapacitive touch screen device similar to that of capacitive sensordevice 100.

When in operation, sensor 108 is used to form a “sensing region” forsensing inputs. It is appreciated that sensor 108 typically comprises aplurality of sensor elements (e.g., the intersections of sensorelectrodes 120 and 130) arranged as a sensor array to form sensor 108.Sensing regions are discussed in more detail below.

Capacitive sensor device 100, when implemented as a touch screen, caninclude a substantially transparent substrate 102 (or a plurality ofsubstantially transparent substrates) having a first set of conductiverouting traces 104 and a second set of conductive routing traces 106patterned (or formed) coupled thereto. Conductive routing traces 104and/or 106 can be utilized for coupling processing system 110 withsensor electrodes (120, 130), arrays of sensor electrodes, and/orconductive traces that form a sensor 108. Although sensor 108 isdepicted as rectangular, other shapes, such as circular are anticipated.Sensor electrodes 120, 130 of sensor 108 can be formed of asubstantially transparent conductive material. Indium tin oxide (ITO)and/or thin, barely visible wires are but two of many possible examplesof a substantially transparent conductive material that can be used toform one or more sensor electrodes 120, 130 or conductive traces ofsensor 108.

Processing system 110 drives sensor electrode(s) with a voltage andsenses resulting respective charge on sensor electrode(s), to acquireone or more measurements of capacitance with respect to sensor 108.Additionally, or alternatively in some embodiments, processing system110 may drive charge on sensor electrode(s) and measure resultingvoltage on sensor electrode(s). Sensor electrode controller 140, in oneembodiment, is used by processing system 110 to selectively drivesignal(s) on one or more sensor electrodes and to selectively receivesignal(s) on one or more sensor electrodes.

In some embodiments capacitive measurer 150 performs capacitancemeasurements (which may be measurements of absolute capacitance ortranscapacitance) based upon received signals. For example, in someembodiments, processing system 110 makes and utilizes a plurality ofcapacitive measurements, associated with individual sensor elements(e.g., the intersections of sensor electrodes 120, 130) of sensor 108,as pixels to create a “capacitive image.” In this manner, processingsystem 110 can capture a capacitive image that is a snapshot of theresponse measured in relation to an input object or objects in thesensing region of sensor 108. Capacitive pixels, images, absolutecapacitance, and transcapacitance are discussed further below.

Such measurement(s) of capacitance by processing system 110 enable thesensing of contact, hovering, or other user input with respect to thesensing region formed by sensor 108. In some embodiments, suchmeasurement(s) are utilized by position, size, and/or type “determiner”160, of processing system 110, to determine positional information withrespect to a user input relative to the sensing region formed by sensor108. Such measurement(s) can additionally or alternatively be utilizedby determiner 160, in some embodiments, to determine input object sizeand/or input object type.

Processing system 110 may be implemented as one or more integratedcircuits and/or discrete components. In one embodiment, processingsystem 110 includes or is implemented within an application specificintegrated circuit (ASIC). In accordance with the embodiments describedherein, such an ASIC can include components such as: sensor electrodecontroller 140; capacitive coupling measurer 150; “determiner” 160;and/or embedded logic instructions. The embedded logic instructions maybe for, but are not limited to, performing such functions as:transmitting and/or receiving on selected sensor electrodes; performingcapacitance measurement(s); and determining contact, position, type,and/or size information with respect an input object interacting with asensing region of sensor 108.

Although described above with respect to a touch screen, capacitivesensor device 100 can also be implemented as a capacitive touchpad,slider, button or other capacitance sensor. For example, substrate 102of capacitive sensor device 100 can be implemented with, but is notlimited to, one or more clear or opaque materials that are utilized as asubstrate for a capacitance sensor Likewise, clear or opaque conductivematerials can also be utilized to form sensor electrodes in sensor 108.

Terminology

The positional information determined by processing system 110 can beany suitable indicia of object presence. For example, the processingsystem can be implemented to determine “zero-dimensional” 1-bitpositional information (e.g., near/far or contact/no contact) or“one-dimensional” positional information as a scalar (e.g., position ormotion along a sensing region). Processing system 110 can also beimplemented to determine multi-dimensional positional information as acombination of values (e.g., two-dimensional horizontal/vertical axes,three-dimensional horizontal/vertical/depth axes, angular/radial axes,or any other combination of axes that span multiple dimensions), and thelike. Processing system 110 can also be implemented to determineinformation about time or history.

Furthermore, the term “positional information” as used herein isintended to broadly encompass absolute and relative position-typeinformation, and also other types of spatial-domain information such asvelocity, acceleration, and the like, including measurement of motion inone or more directions. Various forms of positional information may alsoinclude time history components, as in the case of gesture recognitionand the like. The positional information from the processing system 110facilitates a full range of interface inputs, including use of theproximity sensor device as a pointing device for cursor control,scrolling, and other functions.

As previously described, a capacitive sensor device, such as device 100includes a sensing region. The capacitance sensing device is sensitiveto input by one or more input objects (e.g., fingers, styli, etc.), suchas the position of an input object within the sensing region. “Sensingregion” as used herein is intended to broadly encompass any space above,around, in and/or near the input device in which sensor(s) of the inputdevice is able to detect user input. In a conventional embodiment, thesensing region of an input device extends from a surface of the sensorof the input device in one or more directions into space untilsignal-to-noise ratios prevent sufficiently accurate object detection.The distance to which this sensing region extends in a particulardirection may be on the order of less than a millimeter, millimeters,centimeters, or more, and may vary significantly with the type ofsensing technology used and the accuracy desired. Thus, embodiments mayrequire contact with the surface, either with or without appliedpressure, while others do not. Accordingly, the sizes, shapes, andlocations of particular sensing regions may vary widely from embodimentto embodiment.

Sensing regions with rectangular two-dimensional projected shapes arecommon, and many other shapes are possible. For example, depending onthe design of the sensor array and surrounding circuitry, shielding fromany input objects, and the like, sensing regions may be made to havetwo-dimensional projections of other shapes. Similar approaches may beused to define the three-dimensional shape of the sensing region. Inputobjects in the sensing region may interact with the transcapacitancesensing apparatus.

For example, sensor electrodes (e.g., 120, 130) of an input device, suchas capacitive sensing device 100, may use arrays or other patterns ofsensor electrodes to support any number of sensing regions. As anotherexample, the sensor electrodes may use capacitive sensing technology incombination with resistive sensing technology to support the samesensing region or different sensing regions. Examples of the types oftechnologies that may be used to implement the various embodiments ofthe invention may be found in U.S. Pat. Nos. 5,543,591, 5,648,642,5,815,091, 5,841,078, and 6,249,234.

With continued reference to FIG. 1, various embodiments can utilizetranscapacitive sensing methods based on the capacitive coupling betweensensor electrodes (120, 130). Transcapacitive sensing methods aresometimes also referred to as “mutual capacitance sensing methods.” Inone embodiment, a transcapacitive sensing method operates by detectingthe electric field coupling one or more transmitter sensor electrodes(which are transmitting a signal) with one or more receiver sensorelectrodes. Proximate objects may cause changes in the electric field,and produce detectable changes in the transcapacitive coupling. Aspreviously described, sensor electrodes may transmit as well as receive,either simultaneously or in a time multiplexed manner. Sensor electrodesthat transmit (e.g., sensor electrodes 130) are sometimes referred to asthe “transmitting sensor electrodes,” “driving sensor electrodes,”“transmitters,” or “drivers”—at least for the duration when they aretransmitting. Other names may also be used, including contractions orcombinations of the earlier names (e.g., “driving electrodes” and“driver electrodes.” Sensor electrodes that receive (e.g., sensorelectrodes 120) are sometimes referred to as “receiving sensorelectrodes,” “receiver electrodes,” or “receivers”—at least for theduration when they are receiving. Similarly, other names may also beused, including contractions or combinations of the earlier names.

Transcapacitive sensing schemes may detect changes in capacitivecoupling between transmitter sensor electrodes and receiver sensorelectrodes when a separate electrode (e.g., an external input objectsuch as a human digit or a stylus) is brought near. The output of sensor108 when employing a transcapacitive sensing scheme is often referred toas an “image” or a “capacitive image.” The capacitive image includes ofa plurality of pixels. Pixels of a capacitive image can be referred toas the region in which the transcapacitive coupling between transmittingsensor electrode(s) 130 and receiving sensor electrode(s) 120 can bedetected, a measurement location between a transmitting sensor electrodeand a receiving sensor electrode, or a meeting region betweentransmitter sensor electrode(s) 130 and receiver sensor electrode(s)120.

In this document, the term “electrically drive” may be used to indicatecontrolling some electrical aspect of the driven item. For example, itis possible to drive current through a wire, drive charge onto aconductor, drive a constant or varying voltage waveform onto anelectrode, etc.

In this document, the term “electrically modulating” can includemodulating any appropriate electrical characteristic of the signal, suchas the current or voltage, the amplitude or phase (including sign), somecombination thereof, and the like.

In this document, the term “transmit” or “transmitting” may be used toindicate release of electrical signals, and may imply intentionalrelease of the signals. Transmitting may be done at a low impedancerelative to the capacitive coupling to the receiver.

In this document, the term “sensor electrodes” may include electrodesthat transmit or receive electrical indicia. Some embodiments of theinvention include dedicated transmitting sensor electrodes, dedicatedreceiving sensor electrodes, or both. However, the same physicalelectrode may be used both to transmit and receive. Depending on theembodiment, the transmitting and receiving can be simultaneous or takeplace at different times.

Grounding

In this document, “system ground” (also often referred to as “chassisground,” “device ground,” or “ground”) may indicate a common voltageshared by the system components. For example, a capacitive sensingsystem of a mobile phone may, at times, be referenced to a system groundprovided by the phone's power source (e.g., a charger or battery). Inmany systems, the system ground is connected to or provided by thelargest area electrode in the system. Embodiments may situate orconfigure the system ground with elements farthest from any capacitivesensor electrode(s) used by the system.

The system ground may not be fixed relative to earth or any otherreference. For example, the system grounds for cell phones may beprovided by the respective battery grounds. A battery ground may differfrom the earth ground of an electrical plug connected to the cell phonecharger, the neutral of the charger, and other potential references. Acell phone on a table usually has a floating system ground. A cell phonebeing charged inductively, and thus with no direct connection to thecharger ground, may have a system ground that varies with respect toearth ground. A cell phone being charged with a charger having a ground(e.g., USB ground, wall-socket ground) may still have a system groundthat varies with earth ground, and components of the phone may not bereferenced to earth ground (e.g., where the USB ground terminates in alaptop or where the laptop is floating relative to earth ground). A cellphone being held by a person who is strongly coupled to earth groundthrough free space may be grounded relative to the person; however, theperson-ground may be varying relative to earth ground.

Something that has a voltage substantially constant with respect tosystem ground does not move in voltage (referenced to system ground) asthe system ground's potential changes. For example, an input object maybe substantially at system ground, and not move in voltage significantlyas the system ground's potential changes.

Electrically, any voltage that is effectively fixed relative to thereference may be an effective alternative current (AC) ground, since ithas no AC component. Thus, AC grounded items may not be electricallyconnected together or even to a same ground. Voltages that aresubstantially constant with respect to the reference (e.g., systemground) generally can also serve as AC grounds, and may be equivalent toeach other in sensing/receiving AC capacitive signals. For example, fromthe perspective of a system referenced to system ground, an object at ACground may be at a voltage substantially equal or constantly offset fromsystem ground (at least within the bandwidth of the sensor). Suchobjects are effectively not electrically modulated significantlyrelative to system ground.

Items may be modulated outside of the sensing bandwidth of a capacitivesensing system and effectively be grounded with respect to the sensingsystem. Thus, objects near a sensor device may be modulated in a waythat is not detectable or is filtered out by the sensor device. Forexample, an external object may be modulated at a very high frequencyrelative to the measurement bandwidth of a capacitance sensor device;from that sensor device's perspective, the external object may still beconsidered an AC ground. This is because, within the sensing regime, themodulation of the external object relative to system ground is smallrelative to the signals that the system is trying to detect.

As a specific example, a sensor device may be tuned not to detect (or torespond minimally) to 60 Hz modulation (e.g., main electricitymodulation of fluorescent lights) and 2 GHz modulation (e.g., some phonesignals). If the sensor system can average over enough samples, and hasa bandwidth narrow enough to avoid the noise, then these out-of-bandmodulations do not effectively change the grounded status of theseitems.

Noise

Many sensing devices are made narrow band to ameliorate the effects ofsuch “out-of-band noise.” For absolute capacitance sensing (discussedbelow), this narrow band demodulation (or sampling) may be relative tothe electrical modulation of the sensor electrode. For transcapacitancesensing (also discussed below), the narrow band demodulation may berelative to the electrical modulation of the transmitter. For the mixedabsolute/trans case (discussed below), the narrow band demodulation maybe relative to the electrical modulation of the receiver sensorelectrode, and the transmitter which may be at the same frequency.

In various embodiments, the narrow band filtering may be done in theanalog “front end” domain, the digital “back end” domain, or both. Forexample, a signal can be sampled at twice the modulation rate into twoindependent signals that are 90 degrees out of phase, and a digitalfilter can be used to decode/demodulate this signal. As another example,an I & Q system (where I is intensity and Q is quadrature) may be usedto detect two different signals and distinguish the effects of each fromthe other. Other examples include coded demodulation, FIR/IIR (FiniteImpulse Response/Infinite Impulse Response) filtering, and the like.

Types of Capacitive Measurements

Capacitive sensors and capacitive sensing devices detect capacitancebecause they are affected by changes in electric fields. Changes in theelectric fields are related to how charge flows through the coupledcapacitance(s). Thus, embodiments of capacitive sensors in accordancewith the present technology may use voltage changes, current flow,charge accumulation, etc. to acquire capacitive measurements.

“Absolute capacitance” or “absolute capacitive coupling” may be used toindicate capacitive coupling to system ground. In practice, a sensorelectrode that is electrically modulated relative to system ground maybe used to detect absolute capacitance. Sometimes, the capacitivemeasurement obtained by the sensor electrode may not be pure absolutecapacitance (e.g., when a nearby transmitting sensor electrode ismodulated relative to system ground and the sensor electrode, atranscapacitance may also be introduced). However, absolute capacitancemay dominate in the capacitive measurement if objects near the sensorelectrode are effectively held at “AC ground” from the perspective ofthe system ground. In many cases, objects near the sensor electrode mayinclude external object(s) to be sensed and other electrodes. Theexternal object(s) and other electrodes may or may not be part of thesensing device or electronic system.

In many embodiments, absolute capacitance may also dominate in thecapacitive measurement if any nearby objects that are not substantiallyconstant with respect to system ground, other than the externalobject(s) to be sensed, are electrically modulated in substantially thesame way as the sensor electrode. This may be becauseidentically-modulated other objects do not affect the voltage on thesensor electrode, and do not transfer charge to the sensor electrode. Insome embodiments, these identically-modulated nearby objects may helpguard and shield the sensor electrode from electronic effects.

However, typically, a capacitance measurement may not be purely ofabsolute capacitance, since grounding may not be perfect, modulation maynot be completely identical (and guarding may not be perfect). In someembodiments, the measurement may still be close enough to a measurementof pure absolute capacitance to be treated as such. In otherembodiments, the measurement may be used with one or more othermeasurements to derive the absolute capacitance portion. Thus, it wouldbe possible to measure and calculate the amount of charge that wouldhave been transferred in an ideal absolute capacitive implement.

“Transcapacitance” or “transcapacitive coupling” may be used to indicatecapacitive coupling to one or more transmitting sensor electrodesmodulated relative to system ground. In practice, sensor electrodes maybe used in groups of two or more to sense transcapacitance. One or moresensor electrodes of the group transmit electrical signals while one ormore sensor electrodes of the group receive the transmitted electricalsignals. For example, transcapacitance may be detected where atransmitting sensor electrode electrically modulated relative to systemground emits electrical signals that are received by a receiving sensorelectrode that may not be electrically modulated relative to systemground.

Transcapacitance may dominate in the capacitive measurement where allobjects near the transmitting or receiving sensor electrodes aresubstantially constant relative to system ground. That is, these nearbyobjects may not be electrically modulated relative to system ground. Insuch a case, these nearby objects may also function as guards that helpto prevent noise from reaching the receiving sensor electrode. A nearbyobject may also guard the transmitter sensor electrode from the receiversensor electrode, reducing the capacitive coupling and changing thetranscapacitive measurement.

In some embodiments, a sensor electrode (120, 130) can simultaneouslytransmit and receive; this type of simultaneous transmission andreception may result in a capacitance measurement that includes bothabsolute capacitance and transcapacitance portions.

FIG. 2 shows an example of an external object drawing away part of anelectric field that would otherwise have coupled the transmitter andreceiver sensor electrodes. FIG. 2 illustrates how, in some embodiments,transcapacitive sensing schemes may detect changes in capacitivecoupling between sensor electrodes when a separate electrode (e.g., anexternal object such as a finger) is brought near. In FIG. 2, aconductive external object 215 interacts with a system or device (e.g.,device 100 of FIG. 1) having transmitting sensor electrodes 130 (130-1visible) underlying receiving sensor electrodes 120-1, 120-2 and 120-n.For the portion of sensor 108 shown in FIG. 2, conductive externalobject 215 draws away part of the electric field 217 that wouldotherwise have directly coupled the middle receiving sensor electrode120-2 with the transmitting sensor electrode 130. This interactionchanges the readings obtained from the middle receiving sensor electrode120-2. Also shown is input surface 201, which in one embodiment, is thecover sheet that a conductive external object 215 may touch or come nearin order for the conductive external object 215 to interact with thesystem. It is appreciated that input surface 201 was not illustrated inFIG. 1, so as not to obscure other features of device 100.

Transcapacitive sensing tends to be more localized at overlaps,interconnects, perimeters, and other locations where two electrodes(transmitting and receiving) are disposed in such a way that theirfringing field lines may be affected by an external object. In manyembodiments, transcapacitive sensor electrodes may be close to eachother and may be relatively small, and thus are limited in their abilityto detect inputs far away. The coupling from the transmitting sensorelectrode to the receiving (or shielding) sensor electrode dominates,and may not be affected substantially by external objects that are faraway.

In many mobile devices, the power source (e.g., a cell phone battery fora mobile phone) may provide the system ground or may be driven to besubstantially constant relative to the system ground. Thus, the powersource may be substantially undetectable (e.g., effectivelysubstantially invisible) to a transcapacitive sensing system that drivesthe receiving sensor electrodes substantially stationary with respect tosystem ground. This may be because if the receiving sensor electrode isconstant with respect to system ground, and the power source is constantwith respect to system ground, then there may be no change in electricalpotential between the two, in response to input by one or more externalobjects nearby. However, if the power source on the phone changes involtage with respect to system ground, then it effectively emitselectric signals to the receiving sensor electrodes and can be detectedby a transcapacitive sensing scheme. When the capacitive coupling of atransmitter sensor electrode modulated relative to system ground ischanged it can be detected by the change in coupled charge.

“Mixed capacitance,” “mixed capacitive coupling,” “absolute/transcapacitance,” or “absolute/trans” may be used to indicate capacitivecoupling to both system ground and one or more transmitting sensorelectrodes that may be modulated relative to system ground. To producesuch a mixed capacitance, some or all transmitting and receiving sensorelectrodes may be electrically modulated relative to each other and tosystem ground. This approach works because a receiving sensor electrodemodulated relative to system ground may detect absolute capacitance, andcan detect transcapacitive coupling to any transmitting sensorelectrode(s) modulated differently from system ground and from thereceiving sensor electrode.

Some embodiments distinguish the separate absolute capacitance andtranscapacitance portions. In that case, two or more measurements may betaken. For example, a first measurement may be taken with the receivingsensor electrode(s) modulated in a first way and the transmitting sensorelectrode(s) modulated in a second way. The first and second way may bethe same or different. Then, a second measurement may be taken with thereceiving sensor electrode(s) kept at the first way of modulation andthe transmitting sensor electrode(s) modulated in a third way (such thatthe modulation of the transmitter sensor electrode(s) relative to thereceiver sensor electrode(s) is changed from the second way). Thischange in the transmitting sensor electrode modulation may beaccomplished in a myriad of ways, including but not limited to thefollowing: changing a voltage magnitude; changing the voltage phase;switching between binary ON/OFF voltages; flipping a sign of the voltageswing from positive to negative; changing the voltage swing to be higheror lower; etc. More than two measurements may be taken by someembodiments, such as to reduce noise or to better accommodate a morecomplex combination of transmitting sensor electrodes. Such amulti-measurement approach enables relatively straightforward estimationof the absolute capacitance and transcapacitance contributions.

Some embodiments of the present technology comprise systems that use asame plurality of sensing electrodes in making two different types ofcapacitive measurements. This enables determination of two differentcapacitive measurements for some or all of the plurality of sensorelectrodes. In some embodiments, at least one of the two differentcapacitive measurements includes an absolute capacitance portion, and atleast one of the two different capacitive measurements includes atranscapacitance portion. Some embodiments are configured to use the twodifferent capacitive measurements to determine both the absolutecapacitance and transcapacitance coupling to the sensor electrodeassociated with the two different capacitive measurements. Thus, someembodiments achieve a greater number of capacitance measurements,improved performance (e.g., improved resolution), additionalfunctionality, a greater set of sensing regions, or any combinationthereof than pure absolute capacitance sensing or pure transcapacitivesensing may generate alone.

In some embodiments in accordance with the present technology, the same(or substantially the same) sensor electrodes may be used for bothabsolute and transcapacitive sensing. For example, separate sets ofsensor electrodes for sensing absolute capacitance and transcapacitancemay mean that one set interferes with the other (i.e., the absolutesensing sensor electrodes interfere with the transcapacitive sensingscheme, or vice versa).

Depending on the system design, embodiments of the present technologymay have a sensor electrode that is a dedicated absolute capacitancesensor electrode, a dedicated transmitting sensor electrode fortranscapacitive sensing, a dedicated receiving sensor electrode fortranscapacitive sensing, or a combination thereof. For example, a sensorelectrode may be an absolute capacitance sensor electrode and areceiving sensor electrode for a transcapacitive system. As anotherexample, a sensor electrode may be capable of transmitting and receivingfor a transcapacitive sensing scheme at different times (orsimultaneously). As another example, a sensor electrode may beconfigured as a sensor electrode for absolute sensing as well as becapable of transmitting and receiving for a transcapacitive sensingscheme at different times (or simultaneously). Other such combinationsare possible, and contemplated.

In cases where the transmitting sensor electrode is simultaneously thereceiving sensor electrode, absolute capacitance is generally alsodetected (either pure absolute capacitance if no nearby objects coupletranscapacitively, or mixed if one or more objects coupletranscapacitively). Thus, it is possible in some embodiments to transmitand receive with all sensor electrodes simultaneously (ignoring whendemodulation of the received indicia actually occurs). The receivedindicia would include some absolute capacitance effects in this case.

In many embodiments, the sensor electrodes may not be deflected towardeach other for proper transcapacitive sensing to occur. That is becausethese sensor electrodes detect input in how the input directly changesthe field lines coupling the transmitting and receiving sensorelectrodes (e.g., by drawing away or providing field lines), not by howthe input may change a separation distance between sensor electrodes andthus the capacitive coupling between them. In fact, in many suchembodiments, such deflection may be detrimental for proper capacitivesensing.

In some embodiments, voltage is driven and the resulting current (orcharge) is measured. In some embodiments, current is driven and theresulting voltage is measured. With many suchdrive-current-measure-voltage systems, there may be an absolutecapacitance measurement since one cannot make sure that a sensorelectrode is not modulated with respect to system ground. However, itmay still be possible to determine the absolute and transcapacitivecoupling to an external object.

For example, a first measurement can be taken with some or all of thenon-sensing electrodes (e.g., other sensor electrodes not sensing atthat time and any shield/guard electrodes) driven substantially the sameway as the sensing electrodes. This provides a guarded absolutecapacitance measurement (with the other electrodes providing a guard totranscapacitive coupling to other sensor electrodes). A secondmeasurement can be taken with some or all of the non-sensing electrodessubstantially constant with respect to system ground. This may or maynot be a purely absolute capacitance measurement, since other componentsnearby may not be held substantially constant with respect to systemground; but it provides measurements of the absolute capacitance of thesensing electrodes without the capacitive coupling of the guardingelectrodes, so the later can also be determined. Since these twomeasurements are independent, the transcapacitive and absolutecapacitance components may be derived from them.

This is one example that shows that pure absolute and puretranscapacitance measurements are not necessary to determine exactcontributions from absolute and transcapacitive coupling. Modulating atransmitter in amplitude and phase can provide independent readings fromwhich independent components can be derived. This may apply to more thandrive-current-measure-voltage systems.

Some embodiments may generate the different types of capacitivemeasurements by modulating one or more electrodes that may have beenoriginally included for guarding with different guard signals and makingcapacitive measurements with each different guard electrode modulation.Some embodiments may utilize a first mode where the guard signal createsan over guard (larger in amplitude than the sensor) and a second modewhere the guard signal creates a under guard. By using different guardsignals, two different capacitance measurements can be made, and theabsolute capacitance and transcapacitance coupling may be determined.

Some embodiments may generate the different types of capacitivemeasurements by modulating one or more electrodes between a guard signalthat varies with respect to system ground, and a voltage substantiallyconstant with respect to system ground.

In many embodiments, the modulation of the external object cannot becontrolled by the system. However, in many cases, the electricalpotential of the external object in such a system may be assumed to beconstant relative to system ground, and thus is an AC ground.

FIG. 3 shows a simplified model of a sensor with two sensor electrodesand one external object, in accordance with embodiments of the presenttechnology. In FIG. 3 a model of a system 300 with two sensorelectrodes, sensor electrode 1 (S₁) and sensor electrode 2 (S₂) and oneexternal object 215 (also referred to as “input object” and “I”) thathas been simplified for clarity of explanation is shown in accordancewith embodiments of the present technology. In real world applications,there may be additional external objects (that may or may not beintended as input objects), other sensor electrodes, noise, etc. thatare not included in this simplified model. Also, some systems with onlytwo sensor electrodes and one external object may be more complex. Forexample, the capacitive coupling C₁₂ between sensor electrodes S₁ and S₂may start to depend on the external object capacitive coupling (eitherC_(E1) or C_(E2)). In many embodiments, the capacitance coupling C_(ESg)coupling the external object 215 to system ground 340 may be greater orequal to the sum of C_(E1) and C_(E2).

In FIG. 3, C_(E1) shows the capacitive coupling between sensor electrodeS₁ and the external object 215; C_(E2) shows the capacitive couplingbetween sensor electrode S₂ and the external object 215; and C₁₂ showsthe capacitive coupling between sensor electrode S₁ and sensor electrodeS₂. Capacitance C_(ESg) shows the effective capacitive coupling betweenthe external object 215 and system ground 340. External object 215 maynot be directly coupled to system ground 340 (e.g., not a tetheredstylus hooked to system ground 340, or something else directly hooked tosystem ground 340). Though not illustrated in FIG. 3, it is appreciatedthat external object 215 has some amount of capacitive coupling to freespace (the universe at large), which in turn has some amount ofcapacitive coupling to system ground 340. These two capacitances inseries may provide the capacitive coupling of the external object 215 tosystem ground 340.

Where the capacitive coupling C_(ESg) between external object 215 andsystem ground 340 is relatively small (e.g., often the case for a beadof water or penny on a surface of a touch pad of conventional size), thetranscapacitive coupling C₁₂ between sensor electrodes S₁ and S₂ isnoticeably greater than the absolute capacitive coupling of eithersensor electrodes S₁ or S₂ to system ground 340. Thus, in someembodiments, when processing system 110 (or some portion thereof), ofFIG. 1, differentiates the separate contributions of absolutecapacitance and transcapacitance, this enables differentiating sizes ofobjects (e.g., pennies vs. human-sized objects), thefloating/non-floating state of sensor system ground (e.g., plugged in toa power source vs. floating on a table), etc.

FIG. 4 shows several non-limiting modulation examples, in accordancewith embodiments of the present technology. Referring now to both FIG. 3and FIG. 4 the modulation of sensor electrode S₁ and sensor electrode S₂may be controlled by the a processing system or portion thereof (such asprocessing system 110 and/or sensor electrode controller 140), and bemodified in any number of ways. Table 400, illustrated in FIG. 4,highlights several different modulation options, and the approximateV_(OUT), where: V_(E2)=the electrical potential at external object 215relative to the electrical potential at sensor electrode S₂; V_(E1)=theelectrical potential at external object 215 relative to the electricalpotential at sensor electrode S₁; V₁₂=the electrical potential at sensorelectrode S₁ relative to the electrical potential at sensor electrodeS₂; V_(OUT)≈Q_(OUT)/C_(I), where V_(OUT) is proportional to the chargetransferred between sensor electrode 1 and sensor electrode 2 andinversely proportional to an accumulating capacitance C_(I).

In the “guarded absolute capacitance” case, sensor electrode S₁ andsensor electrode S₂ may be driven in the same way. Square waves areshown in as driving signals, for convenience, and other waveforms (suchas saw tooth, sinusoidal, complex, etc.) may be used. Since sensorelectrode S₁ and sensor electrode S₂ may be driven in the same way,sensor electrode S₁ may have no effect on the output of the sensorcircuitry of a sensor device on S₂. Thus, assuming that the effects ofother nearby objects (e.g., environmental noise, other electrodes, etc.)on sensor electrode S₂ may be ignored, the resulting reading of sensorelectrode S₂ may be considered an absolute capacitance measurement.Since sensor electrode S₁ helps guard sensor electrode S₂ from othernearby objects that may be modulated differently from sensor electrodeS₂, this modulation option may be termed “guarded absolutecapacitance”). Also, as can be seen, this modulation method cannotproduce a direct measurement of C₁₂.

Assuming ideal components, the charge at C_(E2) is the capacitanceC_(E2) times the voltage drop across the capacitor (Q_(E2)=C_(E2)V_(E2))and the effective current flow across C_(E2) is the time derivative(i_(E2)=dQ_(E2)/dt=C_(E2)dV_(E2)/dt). Further assuming that thecomponents of the sensor circuitry are ideal yields a similarrelationship between V_(OUT), C_(I), and the current that flows throughC_(I). Conservation of charge then leads to the approximate V_(OUT)estimate on the right of side of the table 400 of FIG. 4, where V_(OUT)is shown as approximately (C_(E2))(ΔV_(E2))/C_(I). As can be seen, thismodulation enables the direct calculation of C_(E2).

In the “grounded absolute capacitance” case, sensor electrode S₁ is heldconstant relative to system ground (the same as with the externalobject). Sensor electrode S₂ is modulated differently from the externalobject and sensor electrode S₁. In such a case, the voltage V_(E1)=0,and the time derivative dV_(E1)/dt=0. Further, the voltage V₁₂=V_(E2),and the time derivatives are also the same (dV₁₂/dt=dV_(E2)/dt). In sucha case, V_(OUT) is approximately (C₁₂+C_(E2))ΔV_(E2)/C_(I). As can beseen, this modulation yields an absolute capacitance measurement thatincludes a contribution from the system ground that effectively iscoupled through sensor electrode S₁ as well as a contribution throughC_(E2).

In the “shielded transcapacitance” sensor electrode S₂ is held constantrelative to system ground (the same as with the external object), andsensor electrode S₁ is modulated differently from the external objectand sensor electrode S₂. A similar analysis as the above leads to anestimate of V_(OUT) as (C₁₂)(ΔV₁₂)/C_(I), such that the measurementallows a direct calculation of C₂. The position of the external objectcan be indirectly measured by its effect on C₁₂.

In the “mixed absolute/trans” case, both sensor electrodes S₁ and S₂ aremodulated with respect to system ground, and are modulated in oppositionto each other. A similar analysis as the above leads to an estimate ofV_(OUT) as (C_(E2)-2C₁₂)(ΔV_(E2))/C_(I).

It should be understood that the sensor electrodes in a capacitivesensing device may be modulated in numerous manners that are not shownin the table 400 of FIG. 4. For example, both sensor electrode S₁ andsensor electrode S₂ may be modulated differently with respect to eachother, but not be modulated in opposition.

In any case, it can be seen that some of the modulations described aboveare sufficient by themselves for yielding estimates of particularcapacitances (e.g., guarded absolute capacitance for C_(E2) and shieldedtranscapacitance for C₂). Combinations of the different modulationsenable estimates as well (e.g., guarded absolute and grounded absoluteenables calculation of C_(E2) and C₁₂). There are also many methods ofmodulation that would yield information for estimating the differentcapacitances C_(E1), C_(E2), and C₁₂. For example, where there are twounknowns in the resulting analysis, two different modulations that donot produce degenerate equations are sufficient for solving for thesetwo unknowns, or three modulations are sufficient for solving for threeunknowns. Also some capacitances may be modeled, measured or otherwisecharacterized for a particular device or design before the unknowns areto be solved.

Example Sensor Electrodes and Sensor Arrays

As implemented, the sensor electrodes may be of various differentshapes, sizes, layouts, and the like. For example, and referring toFIGS. 5A and 5B, a top view and a side view, respectively, are shown ofa portion of a sensor electrode pattern, in accordance with embodimentsof the present technology. It is appreciated that the arrangements shownin FIG. 5A and 5B can be considered detail views of the sensorelectrodes illustrated in FIG. 1. Sensor electrodes 120-1 and 130-1 areshown as intersecting each other. The cross section AA′, of FIG. 5A isrepresented by FIG. 5B. Capacitive coupling 525 shows where a capacitivecoupling may exist between sensor electrode 120-1 and 130-1, in oneembodiment.

Referring now to FIGS. 6A, 6B and 6C, a top view is shown of examplesensor electrode patterns, in accordance with embodiments of the presenttechnology. FIG. 6A shows sensor electrodes 605 and 610 interleaved witheach other, without intersecting. FIG. 6B shows sensor electrodes 615and 620 interleaved with each other, while intersecting at least once.FIG. 6C shows two sensor electrodes, 625 and 630, where sensor electrode630 is round, and surrounded by sensor electrode 625 in a plane. Inother embodiments, sensor electrode 615 and 620 may be disposed in thesame plane, where a jumper of sensor electrode 615 is formed over sensorelectrode 620, and where a capacitive coupling between sensor electrodesensor electrodes 615 and 620 may primarily be out of the plane. In someembodiments, sensor electrodes 615 and 620 represent one cell or pixel,and a plurality each sensor electrode may be disposed forming multiplecells or pixels of a 2-D capacitive sensor.

FIG. 7 shows a combination of an absolute capacitance sensor and atranscapacitive image sensor, in accordance with embodiments of thepresent technology. For clarity, no substrate is illustrated. In FIG. 7(which can be thought of as an explanatory detail regarding the sensorelectrodes illustrated in FIG. 1), an example layout of four sensorelectrodes is shown in accordance with embodiments of the presenttechnology.

FIG. 7 shows one simple implementation where transmitting sensorelectrodes are overlaid by receiving sensor electrodes. Sensorelectrodes 130-1 and 130-2 are operated as transmitting sensorelectrodes, and sensor electrodes 120-1 and 120-2 are operated asreceiving sensor electrodes. Also shown in FIG. 7 are four capacitances,725, 730, 735 and 740 between the two transmitting and receiving sensorelectrodes. It is appreciated that a greater or lesser number of sensorelectrodes can be arranged in a similar manner.

Referring again to FIG. 1, in one embodiment, the sensor electrodes ofdevice 100 can be utilized as both an absolute capacitance sensor and atranscapacitive sensor, in accordance with embodiments of the presenttechnology. FIG. 1 shows an example rectilinear row-column layout.Although only two column sensor electrodes and two row sensor electrodesare illustrated for purposes of simplicity, it is appreciated that therecan be many more in other embodiments. As illustrated in FIG. 1, the rowof sensor electrodes 130 lie underneath the column sensor electrodes120, and are configured to be further away from an input object duringstandard operation (see e.g., FIG. 2 for an example of an external inputobject 215 in relation to row sensor electrodes 130 and column sensorelectrodes 120). Although illustrated as having similar dimensions, insome embodiments, the row sensor electrodes 130 may have more individualor total surface area that the column sensor electrodes 120, or viceversa.

In an absolute capacitance sensing mode, one or more of the columnsensor electrodes 120 may be modulated with respect to system ground,and used to detect absolute capacitance. At the same time, one or moreof the row sensor electrodes 130 may be modulated in substantially thesame way as the modulated column sensor electrodes 120, and effectivelyfunction as electrical guards.

In a transcapacitance sensing mode, one or more of the row sensorelectrodes 130 may be modulated with respect to system ground and one ormore of the column sensor electrodes 120. This enables sensing of thetranscapacitance between the row and column sensor electrodes 130 and120, respectively.

Taken together, these two modes allow the same sensor electrodes todetect input relatively farther away from the sensor device usingabsolute capacitance measurements, and to detect input relatively closerto the sensor device using transcapacitance measurements (or using acombination of transcapacitive measurements and absolute capacitancemeasurements).

Example Capacitive Sensor Device-Structure

Referring now to FIG. 8, a block diagram of a capacitive sensor device800 is shown in accordance with embodiments of the present technology.In one embodiment, the capacitive sensor device 800 comprises a firstsensor electrode 805, a second sensor electrode 810, and a processingsystem 110B coupled to the first sensor electrode 805 and the secondsensor electrode 810. Sensor electrodes 805 and 810 may be aligned onaxes that are parallel with one another or may be aligned on axes thatare non-parallel with one another. Additionally, sensor electrodes 805and 810 and may be of the same or different surface areas. In oneembodiment, sensor electrode 810 may comprise substantially greatersurface area than sensor electrode 805. In one embodiment, processingsystem 110B is the same or similar to processing system 110 of FIG. 1and includes a sensor electrode controller 140, a capacitive measurer150, and a determiner 160. Sensor electrode controller 140 of processingsystem 110B selectively emits and receives electrical signals on sensorelectrodes which are coupled to processing system 110B. Capacitivemeasurer 150 measures capacitances using the received signals.Determiner 160 determines information, such as positional information ofan input object based upon the capacitance measurements.

In operation, in one embodiment, processing system 110B operates in theabove described manner to acquire a first capacitive measurement 820 byboth emitting and receiving a first electrical signal with first sensorelectrode 805. In one embodiment, processing system 110B also acquires asecond capacitive measurement 830 by emitting and receiving a secondelectrical signal. The first and second capacitive measurements arenon-degenerate. When acquiring the second capacitive measurement 830 oneof either first sensor electrode 805 or second sensor electrode 810 isused to perform the emitting and the other of these two sensorelectrodes is used to perform the receiving. In one embodiment, whensecond sensor electrode 810 is used to perform the emitting needed toacquire second capacitive measurement 830, second sensor electrode 810is substantially larger in surface area (e.g., 25%, 50%, 100%, >100%larger) than first sensor electrode 805. In one embodiment, when firstsensor electrode 805 is used to perform the emitting needed to acquiresecond capacitive measurement 830, first and second capacitivemeasurements 820, 830 are performed contemporaneously. After acquiringthe non-degenerate capacitive measurements, processing system 110B thendetermines first positional information 840 using first and secondcapacitive measurements 820, 830. The two measurements arenon-degenerate when they are not mathematical multiples of each other(e.g., the modulation amplitudes associated with the two measurementsare not just multiples or fractions of each other). For example, in oneembodiment, when processing system 110B uses sensor electrode 805 toboth emit and receive an electrical signal to acquire a first capacitivemeasurement, sensor electrodes 805 is modulated in a first way, and whenprocessing system 110B uses sensor electrode 810 to emit a secondelectrical signal and sensor electrode 805 to receive the secondelectrical signal to acquire a second capacitive measurement, sensorelectrode 810 is modulated in a second way, different than the firstway. This produces first and second capacitive measurements that arenon-degenerate. In one embodiment, the non-degenerate measurements allowfor both the absolute capacitive and transcapacitive components to bederived. First positional information may be output from processingsystem 110B and may describe a position of an input object (e.g.,external object 215 of FIG. 2).

In one embodiment, processing system 110B determines first positionalinformation 840 by making an estimate using the first and secondcapacitive measurements 820, 830. The estimate is of a capacitivecoupling between the first sensor electrode 805 and one of an inputobject and the second sensor electrode 810. When making such anestimate, the first positional information 840 is based at least in parton this estimate of such capacitive coupling. In one embodiment, thecapacitive coupling that is estimated is the capacitive coupling betweenthe first sensor electrode 805 and the input object. In one suchembodiment, processing system 110B is further configured to make asecond estimate using the first and second capacitive measurements 820,830. The second estimate is of a capacitive coupling between firstsensor electrode 805 and second sensor electrode 810.

In one embodiment, processing system 110B of capacitive sensor device800 determines at least one of a size and type of the input object usingthe first and second capacitive measurements 820, 830. The size may bedetermined in various manners, such as being determined as measurements(millimeters) or preset determined based upon a predetermined sizecategory such as small, medium, or large; or grounded or not grounded.The type may be determined from a predetermined list of “types,” such asa finger, thumb, stylus, writing utensil, or water drop.

In one embodiment, processing system 110B of capacitive sensor device800 acquires the first capacitive measurement 820 during a first timeperiod and then acquires the second capacitive measurement 830 during asecond time period. The first and second time periods may becontemporaneous, partially overlay, or be completely different from oneanother. In an embodiment where the time periods are different, this cancomprise processing system 110B modulating second sensor electrode 810with respect to a system ground during the first time period, such thatsecond sensor electrode 810 electrically guards first sensor electrode805. As described in FIG. 4, in one embodiment, processing system 110Bof capacitive sensor device 800 may modulate second sensor electrode 810with respect to a system ground during the first time period bymodulating second sensor electrode 810 substantially similarly to themanner in which first sensor electrode 805 is being modulated duringthis first time period.

In one embodiment, capacitive sensor device 800 further comprises: athird sensor electrode 845 and a fourth sensor electrode 850 that arecoupled to processing system 110B. When additionally sensor electrodesare present, processing system 110B can utilize these additional sensorelectrodes in a similar manner to sensor electrodes 805 and 810 toacquire additional capacitive measurements (which are non-degenerate).For example, in one embodiment, processing system 110B acquires a thirdcapacitive measurement 855 by emitting and receiving a third electricalsignal using third sensor electrode 845 and acquires a fourth capacitivemeasurement 865 by emitting and receiving a fourth electrical signal. Itis appreciated that either one of the third and the fourth sensorelectrodes 845, 850 may be used to perform the emitting while the otherof the third and fourth sensor electrodes 845, 850 performs thereceiving. Processing system 110B then determines second positionalinformation 875 using third capacitive measurement 855 and fourthcapacitive measurement 865.

Example Method of Determining First Positional Information Using a Firstand Second Capacitive Measurement

Referring now to FIG. 9, a flowchart of a method 900 of determiningpositional information using a capacitive sensor device comprising afirst sensor electrode and a second sensor electrode is shown inaccordance with embodiments of the present technology. In oneembodiment, method 900 is a method of operation of device 800 of FIG. 8.Method 900 will be described with reference to the previous descriptionof the operation of capacitive sensor device 800, processing system110B, first sensor electrode 805 and second sensor electrode 810 all ofFIG. 8.

Referring now to 905 of FIG. 9, a first electrical signal is emitted andreceived with the first sensor electrode to acquire a first capacitivemeasurement. In one embodiment, this comprises processing system 110Bemitting and receiving this signal with first sensor electrode 805 whenacquiring first capacitive measurement 820.

Referring now to 910 of FIG. 9, a second electrical signal is emittedand received to acquire a second capacitive measurement. The first andsecond capacitive measurements are non-degenerate. One of the first andsecond sensor electrodes performs the emitting and the other of thefirst and second sensor electrodes performs the receiving. In oneembodiment, this comprises processing system 110B using either sensorelectrode 805 or 810 to perform the emitting, and then using the otherof the two to perform the receiving when acquiring second capacitivemeasurement 830.

Referring now to 915 of FIG. 9, positional information is determinedusing the first and second capacitive measurements, where the first andsecond capacitive measurements are non-degenerate. In one embodiment,processing system 110B determines the positional information from thefirst and second capacitive measurements 820, 830. In one embodiment,the positional information comprises at least one of a position, size,and type of an input object.

In one embodiment, the first electrical signal is emitted and receivedwith first sensor electrode 805 during a first time period to acquirefirst capacitive measurement 820. A second electrical signal is emittedand received during a second time period to acquire second capacitivemeasurement 830. In one embodiment, the first and second time period aredifferent from one another and do not overlap.

Furthermore, in one embodiment, when second sensor electrode 810 is usedto perform the emitting during a second time period, second sensorelectrode 810 is also modulated with respect to a system ground duringthe first time period, such that second sensor electrode 810electrically guards first sensor electrode 805. As has been described inconjunction with FIG. 4, this modulating of second sensor electrode 810can comprise modulating sensor electrode 810 substantially similarly tofirst sensor electrode 805 during the first time period. In other words,both sensor electrode 805 and sensor electrode 810 may be modulated withsimilar electrical signals (e.g., square wave, sine waves, etc.) duringthe first time period.

Some embodiments of method 900 enable lower average power consumptionwith a capacitive sensor device than traditional sensing methods. It isappreciated that, combined absolute and transcapacitance sensing, as hasbeen described herein, may enable power consumption reduction. Forexample, such combined sensing may reduce power consumption in an imagesensing integrated circuit (IC) for a capacitive image sensor such asdevice 100, device 800, device 1000 (FIG. 10), device 1300 (FIG. 13),and/or device 1500 (FIG. 15).

In many embodiments of capacitance imaging touch sensors, a full scan ofall the “pixels” is used to create the image. Sensors shown in FIGS. 1,10, 12, 13, and 15 can be used for imaging. Each “pixel” may beassociated with a spatial location in the touch sensor where a change incapacitive coupling can be determined. The image may be used todetermine the existence or some other information (e.g., location,motion) of one or more input objects.

Using the image to determine the existence of input object(s) may beused to control when the processing system of the touch sensor (often anASIC or other computer chip) goes to sleep and wakes up. In someembodiments, a chip of the touch sensor turns on periodically to lookfor the presence of fingers and goes back to sleep where there is nodetection of such input. Sleeping reduces power consumption, but thistype of operation may still be costly in terms of power. For example,many transcapacitive touch sensors use a scanning scheme, wheretransmitting sensor electrodes are driven in sequence. In a row-columnsensor electrode setup, the rows may be transmitting sensor electrodesthat are driven in sequence, for example, while the columns may bereceiving sensor electrodes that receive in sequence or simultaneously.To extract a full image for detecting the presence of input objects, thecontroller of such a touch sensor scans through one transmitting sensorelectrode at a time and gathers one set of ADC data for eachtransmitting sensor electrode actuation. If the touch sensor has 10transmitting sensor electrodes, for example, generating the full imagewould involve scanning through 10 transmitting sensor electrodes and atleast 10 sets of ADC conversions.

A more power efficient approach may comprise measuring a total absolutecapacitance coupled to some or all of the receiving sensor electrodes ofthe touch sensor, and using that to determine if the processing systemcan go back to sleep or should wake up. In a row-column sensor where thecolumns are the receiving sensor electrodes, this can be accomplishedusing the receiver sensor channel connected to each column sensorelectrode. Taking the same touch sensor with 10 row sensor electrodes asdescribed above, one ADC conversion suffices in most cases. In manyembodiments, much of the savings in power consumption comes from usingthe receiver sensor channels, the CPU, and any memories for a fractionof the time used in the transcapacitive case described earlier.

In many embodiments, a touch sensor processing system may operate mostlyin transcapacitive sensing mode. However, the touch sensor may operatein absolute capacitance sensing mode some of the time (e.g., aftercoming out of power down, often called “wakeup”). When one or moreappropriate input devices (e.g., fingers) are detected, the touch sensormay switch to the transcapacitive operating mode. Where no such inputobjects are detected (e.g., in the absence of finger detection), thetouch sensor may return to a power down mode.

In some embodiments, when no fingers are detected after the first wakeup, the touch sensor goes back to sleep Then, one or more fingers aredetected after the second wake up, the touch sensor switches to thetranscapacitive sensing mode. In one embodiment shown thetranscapacitive sensing mode involves a scanned sensing scheme, and theabsolute sensing mode involves taking all readings simultaneously, andother embodiments may operate otherwise.

Switching between absolute capacitance sensing mode and transcapacitivesensing mode is not limited to controlling when a touch sensor returnsto sleep or stays awake. Starting with an absolute capacitance sensingmode and switching to a transcapacitive sensing mode when certaincriteria have been met may be used in other applications. Examples ofother applications include cases where an initial assessment of theenvironment proximate to the touch sensor, or an initial assessment oftouch sensor functionality, or the like is performed before fullimaging. In some embodiments, this approach is used where timeconstraints mean that there is not enough time to do a full image scan.

Capacitive Sensor Device—At Least One Sensor Electrode inCommon—Acquiring a First and Second Plurality of Capacitive Measurements

Referring now to FIG. 10, a capacitive sensor device 1000 is shown inaccordance with embodiments of the present technology. In oneembodiment, capacitive sensor device 1000 comprises: a first pluralityof sensor electrodes 1005 (shown as 1010 a, 1010 b, 1010 c, 1010 d, 1010e and 1010 f in FIG. 10) aligned along a first axis 1015; a secondplurality of sensor electrodes 1020 (shown as 1025 a, 1025 b, 1025 c and1025 d in FIG. 10) aligned along a second axis 1030 that is non-parallelto the first axis 1015; and a processing system 110C coupled to thefirst plurality of sensor electrodes 1005 and the second plurality ofsensor electrodes 1020. Although all of the sensor electrodes in FIG. 10are illustrated as being of similar size, this may not always be thecase. For example, as with FIG. 8, sensor electrodes 1020 may be ofsubstantially greater surface area than sensor electrodes 1005. It isappreciated that processing system 110C includes similar features(sensor electrode controller 140, capacitive measurer 150, anddeterminer 160) that have been previously described in conjunction withprocessing system 110 (FIG. 1) and processing system 110B (FIG. 8).

In one embodiment, processing system 110C acquires a first plurality ofcapacitive measurements by emitting electrical signals from a first set1045 of the first plurality of sensor electrodes 1005 and receiving theelectrical signals from the first set 1045 of the first plurality ofsensor electrodes 1005 with the first set 1045 of the first plurality ofsensor electrodes 1005. In one embodiment, processing system 110Cacquires a second plurality of capacitive measurements by emittingelectrical signals from a first set 1055 of the second plurality ofsensor electrodes 1020 and receiving the electrical signals from thefirst set 1055 of the second plurality of sensor electrodes 1020 with asecond set 1060 of the first plurality of sensor electrodes 1005. It isappreciated and can be seen from FIG. 10 that, in one embodiment, first1045 and second set 1060 of the first plurality of sensor electrodes1005 have at least one sensor electrode in common. In FIG. 10, thesensor electrode in common is sensor electrode 1010 c, but in otherembodiments, it could be another sensor electrode. In variousembodiments, processing system 110C may acquire the first and secondpluralities of capacitive measurements simultaneously or during separatetime periods.

In one embodiment, processing system 110C determines which sensorelectrodes will be in the second set (e.g., set 1060) of the firstplurality of sensor electrodes 1005, by using the first plurality ofcapacitive measurements. This can facilitate disambiguation, which isdescribed further below. For example, in one embodiment, if acapacitance measurement is indicative of the likely presence of an inputobject being measured by the first set of sensor electrodes; moreoverlapping sensor electrodes may be selected. While in anotherembodiment, if no input object is likely based on the first capacitancemeasurement, fewer or no overlapping sensor electrodes may be in thesecond set.

In one embodiment, the capacitive sensor device 1000 further comprisesan input surface associated with the capacitive sensor device 1000. Soas not to obscure features, no input surface is illustrated in FIG. 10,however, input surface 201 of FIG. 2 is one example of such an inputsurface. In an embodiment with such an input surface, processing system110C is configured to determine a first position estimate of an inputobject using the first plurality of capacitive measurements. In oneembodiment, the first position estimate may locate the input objectrelatively farther from the input surface. Processing system 110C canthen determine a second position estimate of the input object using thesecond plurality of capacitive measurements, where the second positionestimate locates the input object relatively closer to the inputsurface.

In another embodiment, the processing system 110C is further configuredto determine at least one of a size, type, and a capacitive coupling tosystem ground of an input object using the first and second pluralitiesof capacitive measurements. It is appreciated that in one embodiment,determiner 160 can perform such determination(s) utilizing techniqueswhich have previously been described herein.

Example Method of Sensing Using a Capacitive Sensor Device

Referring now to FIG. 11, a method 1100 of sensing using a capacitivesensor device, such as capacitive sensing device 1000 is described, inaccordance with one embodiment. As illustrated, capacitive sensor device1000 comprises a first plurality of sensor electrodes 1005 aligned alonga first axis 1015 and a second plurality of sensor electrodes 1020aligned along a second axis 1030 that is non-parallel to the first axis1015. Method 1100 will be described with reference to the previousdescription of the operation of capacitive sensor device 1000,processing system 110C, and sensor electrodes illustrated in device1000.

Referring now to 1105 of FIG. 11, in one embodiment, electrical signalsfrom a first set of a first plurality of sensor electrodes are emitted.In one embodiment, this comprises sensor electrode controller 140 ofprocessing system 110C selecting sensor electrodes and provingelectrical signals to be emitted. In one embodiment, sensor electrodes1005 are the first plurality of sensor electrodes and sensor electrodes1045 are the first set of sensor electrodes from which the electricalsignals are emitted.

Referring now to 1110 of FIG. 11, in one embodiment, the electricalsignals from the first set 1045 of the first plurality of sensorelectrodes 1005 are received with a second set 1060 of the firstplurality of sensor electrodes 1005 to acquire a first plurality ofcapacitive measurements. It is appreciated that, in one embodiment,controller 140 receives/acquires the electrical signals and capacitivemeasurer 150 determines the capacitances based on the receivedelectrical signals.

Referring now to 1115 of FIG. 11, in one embodiment, electrical signalsare emitted from the second set 1060 of the first plurality of sensorelectrodes 1005. In one embodiment, it is appreciated that the first set(e.g., 1045) and second set (e.g., 1060) have at least one sensorelectrode (e.g., 1010) in common.

Referring now to 1120 of FIG. 11, in one embodiment, second electricalsignals from the second set 1060 of the first plurality of sensorelectrodes 1005 are received with a first set 1055 of the secondplurality 1020 of sensor electrodes. In the manner previously described,these electrical signals are used to acquire a second plurality ofcapacitive measurements.

As has previously been described in conjunction with description of FIG.10, in one embodiment, the electrical signals may be emitted from thefirst set 1045 of the first plurality of sensor electrodes 1005 whileelectrical signals are simultaneously emitted from the second set 1060of the first plurality of sensor electrodes of 1005.

In one embodiment, the second set (e.g., 1060) of the first plurality ofsensor electrodes 1005 is determined using the first plurality ofcapacitive measurements. For example, in one embodiment, processingsystem 110C determines which sensor electrodes will be in the second set(e.g., set 1060) of the first plurality of sensor electrodes 1005, byusing the first plurality of capacitive measurements. This canfacilitate disambiguation, which is described further below. Forexample, in one embodiment, if a capacitance measurement is indicativeof the likely presence of an input object being measured by the firstset of sensor electrodes; more overlapping sensor electrodes may beselected. While in another embodiment, if no input object is likelybased on the first capacitance measurement, fewer or no overlappingsensor electrodes may be in the second set.

Some embodiments of device 1000 and method 1100, as well as othermethods and devices described herein, use the ability to sense bothabsolute capacitance and transcapacitance to enable individual sensingschemes, to enable additional functionality, and/or for other purposes.Various techniques and reasons for utilizing these types of sensing inalternation or combination have been previously described herein, andmore discussion appears below.

Use of Both Absolute and Transcapacitive Sensing by a Sensor Device

In many embodiments, the absolute capacitance sensing may enable sensingfurther away than does transcapacitive sensing. For example, some mobilephones may be enabled with capacitive sensors. Many of these mobilephones locate capacitive sensor electrodes close to each other, andclose to one face (e.g., the front face) of the device. The batteries ofthe devices may be located close to an opposite face (e.g., the backface). The battery often supplies the system ground of the device, andcan be considered a large electrical object to which the sensorelectrodes may capacitively couple. Sometimes, part of the housing maybe coupled to the system ground provided by the battery and the size ofthis large electrical object increases.

Driven in an “absolute capacitance sensing” method, significant fieldlines run between the sensor electrodes and the effective electrodesupplied by the battery. The relatively large distance between thecapacitive sensor electrodes and the battery/grounded housing enablescapacitive sensing of objects relatively far away.

In contrast, driven in a “transcapacitive” method, significant electricfield lines run between the transmitting and receiving sensorelectrodes, and less so between the sensor electrodes and the effectiveelectrode supplied by the battery. Given the relatively fewer fieldlines running into free space from the sensor electrodes (since most runbetween the sensor electrodes), the ability of these sensor electrodesto sense far away from the sensor electrodes is limited. Theoretically,it is still possible to sense as far as in the absolute capacitancecase, since the electric field coupling transmitting and receivingsensor electrodes can still be affected by objects relatively far fromthe sensor electrodes. However, this may not be feasible for manyembodiments due to limitations on the size and spacing of theelectrodes. Practically, such effects by objects relatively far from thesensor electrodes may be so small that they are on the level of noise,or the costs of circuitry that can sense such small changes may beprohibitive, or the like.

Also, the transcapacitive sensing schemes may enable more independentmeasurements than absolute sensing in many embodiments. Measurementsthat are more independent provide more information about what is sensed,and these measurements may be used to increase sensor performance (e.g.,sensor accuracy, etc.).

With appropriate transcapacitive sensor design, the number oftransmitting and receiving combinations drives the number ofmeasurements that can be taken with transcapacitive sensor systems. Incomparison, with appropriate absolute sensor design, the number ofsensor electrodes drives the number of measurements that can be takenwith absolute capacitance systems. Thus, transcapacitive systems maygenerate more independent measurements with the same number of sensorchannels than absolute capacitance systems.

Embodiments in accordance with the present technology may provide for acombination absolute-trans system. A combination-sensing-scheme systemmay increase the number of sensor measurements obtainable by the sensordevice for each of the sensor electrodes than either scheme used alone.Also, a combination system can utilize transcapacitive and absolutecapacitance sensing schemes in detecting and responding to a same userinput. Absolute capacitance measurements can provide information aboutthe user input when it is relatively far away, and transcapacitivemeasurements can provide information about the user input when it isrelatively close. These enable a system to respond to a wider set ofuser input types and locations.

As another example, both absolute and transcapacitive measurements canbe used to derive information about the user input when it is relativelyclose. In some embodiments, absolute capacitance sensing may provideprofile information, and transcapacitance sensing with the same sensorelectrodes may provide imaging information. Using both types ofmeasurements together can provide information unavailable with only oneof the sensing schemes (e.g., type of input, size of input), a betterdetermination of the location of input object(s), and the like. Asanother alternative, both absolute and transcapacitive measurements canbe used to provide information about the user input when it isrelatively far.

Absolute capacitance and transcapacitance sensing may be used incombination. For example, some embodiments may control system wake-upusing measurements obtained in an absolute capacitive mode, and use atranscapacitive mode for other functionalities such as capacitiveimaging. Some embodiments may use measurements obtained in an absolutecapacitive mode to determine general user input location andtranscapacitive sensing for higher resolution information about the userinput. Some embodiments may use absolute capacitive coupling to modelfinger coupled noise, such as for testing purposes.

Some embodiments superimpose absolute capacitance and transcapacitancesensing. For example, a driven voltage system may have a series ofsensor electrodes where each sensor electrode is measured while beingmodulated. In such a case, an absolute capacitance may be obtained(e.g., for profiles of one or more fingers) at the same time atranscapacitance is obtained (e.g., for full capacitive images or forpartial capacitive images as needed to disambiguate the profiles).

In some embodiments, one measurement is taken, and then anothermeasurement is taken after the phase has been shifted. This allowsdetermination of the absolute and transcapacitance portions in manycases. For example, with proper phase shifting (such as to an oppositephase), one measurement may reflect the sum of the absolute capacitivecoupling to the external object (and associated system ground) and thetranscapacitive coupling to the guard electrode(s), while the othermeasurement may reflect the difference between the absolute capacitivecoupling to the external object (and associated system ground) and thetranscapacitive coupling to the guard electrode(s). Thus, someembodiments may have sensor electrodes with references that aremodulated relative to each other, where those sensor electrodes aresimultaneously both receiving and transmitting sensor electrodes. Thismay help optimize measurement power, increase signal to noise, andimprove interference tolerance.

Disambiguation Using Transcapacitive Sensing

FIG. 12 shows a capacitance sensor device in accordance with embodimentsof the present technology. Referring now to FIG. 12, the capacitancesensor devices 1200 and has a first set of sensor electrodes 1215disposed along a first axis 1220 and a second set of sensor electrodes1225 disposed along a second axis 1230. The two axes are shown as the Xand Y axes of a Cartesian coordinate system, although other axes orcoordinate systems may be used. Additionally, the sensor electrodesshown are long rectangles for simplicity of illustration and discussion.However, it is appreciated that many other shapes are suitable. The Xand Y positions are further labeled for a range of X [0 . . . 10] and Y[0 . . . 10], although other ranges may be used.

Referring to FIG. 12, the illustrated sensor electrodes can be driven inan absolute sensing scheme, and used to produce separate one-dimensional(1D) profiles of changes in capacitive coupling. These 1D profiles canbe thought of as silhouettes or projections of changes in capacitivecoupling along the axes, and can be used to determine the position of aninput object, such as input object 1205 a and 1205 b. For example device1200 may determine positions, based upon the peaks of Cx and Cy.

FIG. 12 shows that pairs of input objects, 1205 a and 1205 b, and 1210 aand 1210 b, in different locations at different times, may produce thesame 1D profiles. The capacitance sensor device 1200 has a first set ofsensor electrodes 1215 disposed along a first axis 1220, and a secondset of sensor electrodes 1225 disposed along a second axis 1230.Specifically, FIG. 12 shows a first pair of input objects 1205 a and1205 b located at (3.0, 6.5) and (7.0, 2.5), respectively, and a secondpair of input objects 1210 a and 1210 b located at (3.0, 2.5) and (7.0,6.5), respectively. Either of the pairs may produce the profiles shownin FIG. 12. Thus, the positions of the input objects 1205 a, 1205 b,1210 a and 1210 b may be ambiguous.

Depending on the circumstances (e.g., size of input objects, types ofinput objects, nearby noise, sensor resolution and accuracy, etc.), thenumber of input objects may also be ambiguous. For example, three inputobjects at three of the positions (3.0, 6.5), (7.0, 2.5), (3.0, 2.5),and (7.0, 6.5) may produce the same or similar profiles to those shownin FIG. 12. Similarly, four input objects at all four of the positions(3.0, 6.5), (7.0, 2.5), (3.0, 2.5), and (7.0, 6.5) may also produce thesame or similar profiles.

Some embodiments of capacitive sensing devices described herein use thehistory of input object number and locations, relative magnitudes of theprofile peaks or troughs, or other information to disambiguate. Someembodiments of capacitive sensing devices described herein introduceadditional sensor electrodes or additional axes of sensor electrodes todisambiguate. However, these methods of disambiguation may not becompletely conclusive or require additional electrodes.

To disambiguate in such instances, transcapacitance sensing may be usedwith at least a portion of the electrodes. For example, some systems mayregularly shift from absolute capacitance sensing to transcapacitivesensing at regularly periods to help disambiguate. As another example,some systems may default to absolute capacitance sensing, and transitionto transcapacitive sensing in response to ambiguity.

Transcapacitance sensing may be used to image parts of or entire sensingregions. For example, some systems may scan the entire sensing regionand produce a 2D image of changes in capacitive coupling for an entiresurface associated with the sensing region. The system may then use theimage to ascertain the number of input objects and their locations. Asanother example, some systems may sense transcapacitance only in selectportion(s) of the sensing region, such as in regions including or nearpotential input object locations. Such selective transcapacitancesensing may be achieved by transmitting and receiving on sensorelectrodes that couple transcapacitively proximate to the potentiallocations of the input objects. This approach can produce a “partialimage” sufficient to differentiate between true and false input objectlocations.

One method of disambiguating the situation shown in FIG. 12 usingtranscapacitive sensing is shown in accordance with embodiments of thepresent technology. In response to an ambiguous situation such as theone shown in FIG. 12, device 1200 may convert to sensingtranscapacitance. Device 1200 may detect transcapacitance couplingbetween sensor electrodes that intersect near the potential locations ofinput objects. Input objects such as fingers may cause the greatestchange in transcapacitive coupling at junctions near transmitting andreceiving sensor electrodes. Thus, examining how transcapacitivecoupling has changed from a baseline, or some other reference, mayenable disambiguation of the position(s) or number(s) of input objects(or both).

In FIG. 12, in accordance with embodiments of the present technology,four horizontal sensor electrodes 1240 a, 1240 b, 1240 c and 1240 d areshown as transmitting and two vertical sensor electrodes 1235 a and 1235b are shown as receiving in a disambiguation scan. It should beunderstood that the transmitting (and the receiving) may be donesimultaneously or in sequence. It should also be understood that thenumbers and status as transmitting and receiving sensor electrodesdiffer between designs and circumstances. For example, by observing thatthe capacitive couplings between sensor electrodes 1235 a and 1240 a,sensor electrodes 1235 a and 1240 b, sensor electrodes 1235 b and 1240 cand sensor electrodes 1235 b and 1240 d are reduced near input objects1205 a and 1205 b, it is possible to disambiguate input objects 1205 aand 1205 b from 1210 a and 1210 b.

Some embodiments of the present technology comprise a capacitive imagingsystem with a series of sensor electrodes disposed over another series,in an overlapping manner. This configuration enables acquisition of atranscapacitive image of the user input. This configuration also enablessensing of far-field proximity input. For example, some sensorelectrodes may operate as absolute capacitance sensor electrodes forsensing absolute capacitances, and as receiving sensor electrodes forsensing transcapacitances. As another example, some sensor electrodesmay operate as shields or guards in an absolute capacitance sensingmode, and transmitting sensor electrodes in a transcapacitance sensingmode.

Capacitive Sensor Device—Making Estimates of a Position of Input ObjectsUsing First and Second Plurality of Capacitive Measurements

Referring now to FIG. 13, a capacitive sensor device 1300 is shown inaccordance with embodiments of the present technology. In oneembodiment, capacitive sensor device 1300 comprises: a first pluralityof sensor electrodes 1305 (shown as 1310 a, 1310 b, 1310 c, 1310 d, 1310e and 1310 f in FIG. 13) that are aligned along a first axis 1315; asecond plurality of sensor electrodes 1320 (shown as 1325 a, 1325 b,1325 c and 1325 d in FIG. 13) that are aligned along a second axis 1330which is non-parallel to the first axis 1315; and a processing system110D which is coupled to the first plurality of sensor electrodes 1305and the second plurality of sensor electrodes 1320. As is illustrated,the second plurality of sensor electrodes 1320 forms a matrix patternwith the first plurality of sensor electrodes 1305. Although all of thesensor electrodes in FIG. 13 are illustrated as being of similar size,this may not always be the case. For example, sensor electrodes 1320 maybe of substantially greater surface area than sensor electrodes 1305. Itis appreciated that processing system 110D includes similar features(sensor electrode controller 140, capacitive measurer 150, anddeterminer 160) that have been previously described in conjunction withprocessing system 110 (FIG. 1), processing system 110B (FIG. 8), andprocessing system 110C (FIG. 10).

In one embodiment, processing system 110D acquires a first plurality ofcapacitive measurements by selectively emitting and receiving firstelectrical signals using a first plurality of sensor electrodes (e.g.,sensor electrodes 1305). It is appreciated that controller 140, in oneembodiment, selects the sensor electrodes and controls the sensing andreceiving, while capacitive measurer 150 performs capacitivemeasurements based up received signals. Processing system 110D thenutilizes the first plurality of capacitive measurements to make a firstestimate of a position 1340 of at least one input object using the firstplurality of capacitive measurements. In one embodiment, determiner 160of processing system 110D determines position estimates. The inputobject may be an object such a stylus, human digit, or writing utensil,and may comprise more than one (e.g., two or more input objects).

In one embodiment, processing system 110D select a first set 1345 (shownas 1310 a, 1310 b and 1310 c in FIG. 13) of the first plurality ofsensor electrodes 1305 and a first set 1350 (shown as 1325 a and 1325 bin FIG. 13) of the second plurality of sensor electrodes 1320 using thefirst estimate 1340 as a basis for the selection. For example, such aselection may be made in an embodiment where the first measurementindicated that an input object had been sensed relative to the upperleft quadrant of the matrix formed by sensor electrodes 1305 and 1320.Processing system 110, then acquires a second plurality of capacitivemeasurements by emitting second electrical signals with one of the firstsets 1345 and 1350 of the first 1305 and the second 1320 plurality ofsensor electrodes, respectively, and by receiving the second electricalsignals with another of the first sets 1345 and 1350 of the first 1305and second 1320 plurality of sensor electrodes. Processing system 110Dthen makes a second estimate 1360 of the position of the at least oneinput object using the second plurality of capacitive measurements. Inone embodiment, determiner 160 makes this second position estimate.

It is appreciated that the first plurality of capacitive measurementsand the second plurality of capacitive measurements may be acquired byprocessing system 110D during first and second time periods,respectively. The first and second time periods may be the same, ordifferent from one another. In one embodiment, where the first timeperiod is different from the second time period, processing system 110Delectrically guards the first plurality of sensor electrodes 1305 bymodulating at least one sensor electrode of the second plurality ofsensor electrodes 1320 with respect to a system ground during the firsttime period. Techniques for such modulation have been previouslydescribed herein.

In one embodiment, where two position estimates are made, the secondposition estimate 1360 is of finer resolution than the first estimate1340. In one embodiment, where two position estimates are made, thefirst estimate 1340 comprises possible locations of the at least oneinput object, and the second estimate 1360 is a disambiguation of thepossible locations. It is appreciated that one or more of the positionestimates (1340, 1360) may be provided as an output from processingsystem 110D.

It is appreciated that, in one embodiment, processing system 110D isfurther configured to determine at least one of a size, a type, and acapacitive coupling to system ground of an input object using the first1305 and second 1320 pluralities of capacitive measurements. One or moreof these can additionally or alternatively be determined by determiner160. A determined size, type, and/or capacitive coupling can be providedas an output from processing system 110D.

Example Method of Capacitive Sensing

Referring now to FIG. 14, a method 1400 of sensing using a capacitivesensor device such as capacitive sensor device 1300 is described, inaccordance with one embodiment. As illustrated, capacitive sensor device1300 comprises a first plurality of sensor electrodes 1305 aligned alonga first axis 1315 and a second plurality of sensor electrodes 1320aligned along a second axis 1330 that is non-parallel to the first axis1315.

Referring now to 1405 of FIG. 14, in one embodiment, first electricalsignals are emitted and received with a first plurality of sensorelectrodes in order to acquire a first plurality of capacitivemeasurements. In one embodiment, this comprises controller 140 ofprocessing system 110D providing one or more electrical signals andselecting a first plurality of sensor electrodes 1345 for emitting andreceiving. Based upon the received electrical signals, in oneembodiment, capacitive measurer 150 generates a plurality of capacitivemeasurements.

Referring now to 1410 of FIG. 14, in one embodiment, a set of firstestimates of positions of at least one input object is made using thefirst plurality of capacitive measurements. It is appreciated that theremay be two or more input objects for which estimates are made. In oneembodiment, determiner 160 estimates the position(s) and provides thefirst set of estimates.

Referring now to 1415 of FIG. 14, in one embodiment, a first set of thefirst plurality of sensor electrodes and a first set of the secondplurality of sensor electrodes is determined using the first set ofestimates of the positions. Processing system 110D makes such adetermination, in one embodiment, based on a potential location where aninput object appears to have been sensed. In one embodiment, processingsystem 110D select a first set 1345 (shown as 1310 a, 1310 b and 1310 cin FIG. 13) of the first plurality of sensor electrodes 1305 and a firstset 1350 (shown as 1325 a and 1325 b in FIG. 13) of the second pluralityof sensor electrodes 1320 using the first estimate 1340 as a basis forthe selection. For example, such a selection may be made in anembodiment where the first measurement indicated that an input objecthad been sensed relative to the upper left quadrant of the matrix formedby sensor electrodes 1305 and 1320. Such a determination and selectionof sets of sensor electrodes is made, in one embodiment, for purposes ofdisambiguation. Techniques for disambiguation have been previouslydescribed herein.

Referring now to 1420 of FIG. 14, in one embodiment, second electricalsignals are emitted with one of the first sets of the first and secondplurality of sensor electrodes and the second electrical signals arereceived with the other of the first sets of first and second pluralityof sensor electrodes to acquire a second plurality of capacitivemeasurements. As previously describe, in one embodiment, processingsystem 110D provides the second electrical signals and selectivelydrives the signals and receives the signals. For example, in oneembodiment, the second electrical signals are emitted using sensorelectrodes 1345 or sensor electrodes 1350 and then received with thesensor electrodes of these which were not used for emitting.

Referring now to 1425 of FIG. 14, in one embodiment, a second estimateof the position of the at least one input object is made using thesecond plurality of capacitive measurements. As previously described,this can comprise determiner 160 of processing system 110D making thissecond estimate of position, which may be finer the first estimate ofposition. For example, the set of first estimates may comprisesidentifications of possible locations of the at least one input object,while the second estimate comprises a disambiguation of these possiblelocations.

Capacitive Sensor Device—Emitting and Receiving Electrical Signals toAcquire a First and Second Plurality of Capacitive Measurements

Referring now to FIG. 15, a capacitive sensor device 1500 is shown inaccordance with embodiments of the present technology. In oneembodiment, capacitive sensor device 1500 comprises: a first pluralityof sensor electrodes 1505 that are aligned along a first axis 1510; asecond plurality of sensor electrodes 1515 that are aligned along asecond axis 1520 which is non-parallel to said first axis; and aprocessing system 110E coupled to the first plurality of sensorelectrodes 1505 and the second plurality of sensor electrodes 1515. Asis illustrated, the second plurality of sensor electrodes 1515 forms amatrix pattern with the first plurality of sensor electrodes 1505.Although all of the sensor electrodes in FIG. 15 are illustrated asbeing of similar size, this may not always be the case. For example, aswith FIG. 8, sensor electrodes 1515 may be of substantially greatersurface area than sensor electrodes 1505. It is appreciated thatprocessing system 110E includes similar features (sensor electrodecontroller 140, capacitive measurer 150, and determiner 160) that havebeen previously described in conjunction with processing system 110(FIG. 1), processing system 110B (FIG. 8), processing system 110C (FIG.10), and processing system 110D (FIG. 13).

In one embodiment, processing system 110E emit and receive firstelectrical signals with a first plurality of sensor electrodes 1505during a first time period in order to acquire a first plurality ofcapacitive measurements. This may comprise controller 140 generatingthese first electrical signals and selecting the first plurality ofelectrodes 1505. Once the signals are received, capacitive measurer 150determines a plurality of capacitive measurements. In one embodiment,processing system 110E electrically guards the first plurality of sensorelectrodes 1505 by modulating the second plurality of sensor electrodes1515 during the first time period. Examples of such electrical guardinghave been previously described herein, such as in conjunction withdescription of FIG. 4. In one embodiment, processing system 110E emitssecond electrical signals with second plurality of sensor electrodes1515 during a second time period that is different from the first timeperiod. Processing system 110E then receives the second electricalsignals with the first plurality of sensor electrodes 1505 during thesecond time period and uses the signals to acquire a second plurality ofcapacitive measurements.

In one embodiment, processing system 110E electrically guards the firstplurality of sensor electrodes 1505 by modulating the second pluralityof sensor electrodes 1515 during the first time period. This cancomprise modulating substantially all of the second plurality sensorelectrodes 1515 in a manner that is substantially similar to themodulation of at least one of the first plurality of sensor electrodes1505 during the first time period. Again it is appreciated that suchtechniques have previously been described herein, in particular withdiscussion of FIG. 4.

In one embodiment, processing system 110E electrically guards the firstplurality of sensor electrodes 1505 by modulating the second pluralityof sensor electrodes 1515 during the first time period. This cancomprise modulating a subset of the second plurality of sensorelectrodes 1515 substantially similarly to an amplified version of amodulation of at least one the first plurality of sensor electrodes 1505during the first time period.

In one embodiment, the processing system 110E emits second electricalsignals with second plurality of sensor electrodes 1515 during a secondtime period that is different from the first time period. This cancomprise emitting during different portions of the second time periodusing different sensor electrodes of the second plurality of sensorelectrodes 1515. This can also comprise emitting differently modulatedelectrical signals using different sensor electrodes of the secondplurality of sensor electrodes 1515 simultaneously for such emissions.

In one embodiment, the processing system 110E determines a position ofan input object using at least one of the first and second pluralitiesof capacitive measurements. This can comprise determiner 160 making thisposition determination. Furthermore, in one embodiment, processingsystem 110E makes a first estimate 1540 using the first and secondplurality of capacitive measurements and makes a second estimate 1545using the first and second plurality of capacitive measurements. Thefirst estimate 1540 is of a capacitive coupling between a first sensorelectrode and an input object and the second estimate 1545 is of acapacitive coupling between the first sensor electrode and a secondsensor electrode. Performance of such estimates has been previouslydescribed herein. In one embodiment, determiner 160 of processing system110E also determines at least one of a size, type, and grounding of aninput object using the first and second pluralities of capacitivemeasurements. It is appreciated that the estimates and determinationscan be provided as outputs from processing system 110E.

Example Method of Capacitive Sensing

Referring now to FIG. 16, a method 1600 of sensing using a capacitivesensor device 1500 is described, in accordance with one embodiment. Asillustrated, capacitive sensor device 1500 comprises a first pluralityof sensor electrodes 1505 that are aligned along a first axis 1510 and asecond plurality of sensor electrodes 1515 that are aligned along asecond axis 1520 that is non-parallel to first axis 1510.

Referring now to 1605, in one embodiment, first electrical signals areemitted and received with the first plurality of sensor electrodesduring a first time period to acquire a first plurality of capacitivemeasurements. In one embodiment, this comprises controller 140 ofprocessing system 110E providing one or more electrical signals andselecting a first plurality of sensor electrodes, such as sensorelectrodes 1505, for emitting and receiving. Based upon the receivedelectrical signals, in one embodiment, capacitive measurer 150 generatesa plurality of capacitive measurements.

Referring now to 1610 of FIG. 16, in one embodiment, sensor electrodesof a second plurality of sensor electrodes are modulated during thefirst time period, to electrically guard the first plurality of sensorelectrodes. In one embodiment, controller 140 provides these electricalsignals to sensor electrodes 1515, which constitute the second pluralityof sensor electrodes. In one embodiment, substantially all of the secondplurality sensor electrodes 1515 are modulated substantially similarlyto the modulation of at least one of the first plurality of sensorelectrodes 1505 during the first time period. In another embodiment, asubset of the second plurality of sensor electrodes 1515 is modulatedsubstantially similarly to an amplified version of a modulation of atleast one the first plurality of sensor electrodes during the first timeperiod.

Referring now to 1615 of FIG. 16, in one embodiment, second electricalsignals are emitted with the second plurality of sensor electrodesduring a second time period different from the first time period. In oneembodiment, this comprises processing system 110E emitting the secondelectrical signals on sensor electrodes 1515.

Referring now to 1620 of FIG. 16, in one embodiment, the secondelectrical signals are received with the first plurality of sensorelectrodes during the second time period to acquire a second pluralityof capacitive measurements. In one embodiment, this comprises processingsystem 110E receiving the second electrical signals with sensorelectrodes 1505 and the acquiring the capacitive measurements from thereceived signals.

In one embodiment, processing system 110E emits second electricalsignals with the second plurality of sensor electrodes 1515 during asecond time period that is different from the first time. This cancomprise emitting non-concurrently during the second time period usingdifferent individual sensor electrodes of second plurality of sensorelectrodes 1515. This can also comprise simultaneously emittingdifferently modulated electrical signals using different individualsensor electrodes of second plurality of sensor electrodes 1515.

In one embodiment, method 1600 further comprises determining a positionof an input object using at least one of the first and secondpluralities of capacitive measurements. As has been previouslydescribed, determiner 160 of processing system 110E, makes such positiondeterminations (and other determinations such as size, type, andgrounding determinations) from capacitive measurements.

Additionally, in one embodiment, method 1600 further comprises making afirst estimate using the first and second capacitive measurements, andmaking a second estimate using the first and second capacitivemeasurements. The first estimate is of a capacitive coupling between thea sensor electrode of sensor electrodes 1505 and an input object, andthe second estimate is of a capacitive coupling between this sensorelectrode of sensor electrodes 1505 and a second sensor electrode ofsensor electrodes 1515. Based upon these estimates, processing system110E (determiner 160) determines at least one of a size, type, andgrounding of an input object.

As has been described herein, in some embodiments, sensor electrodes mayhave functions such as guarding or shielding the sensor from electricalnoise, mitigating sensitivity of the buttons to moisture, and the like.As has been described herein in conjunction with FIG. 4, these sensorelectrodes may accomplish these functions with modulations differentfrom those used for transcapacitance sensing.

Example “Button” Capacitive Sensing Devices

In some embodiments, a capacitive sensor device as described herein,includes a set of sensor electrodes configured to form discretecapacitive buttons. In many embodiments, the capacitive buttons areenabled by one sensor electrode configured to sense absolute capacitanceper capacitive button (although that need not be the case). In such adesign, the absolute capacitive coupling between an input object (e.g.,a finger or stylus) and a button sensor electrode is drivenpredominantly by the area of overlap between the two. In someembodiments, the largest area of overlap, and thus the largest effect onthe button, occurs when the input object is centered on the buttonsensor electrode.

The degree of absolute capacitive coupling provides enough informationfor some functions. However, more information about the user input maystill be determined, or particular issues associated with absolutecapacitance sensing may still be determined, for other functions.Examples of user input information include the size of the input object,the type of input object, improved location or motion estimates aboutthe input object, information about the input object outside of theabsolute capacitance sensing region, estimates of the off-centerednessof the input object, and the like. Examples of issues associated withabsolute capacitance sensing may include sensitivity to moisture, andpotential inability to distinguish between an input object sliding infrom the side and the input object coming straight down from above.Sensing transcapacitance in addition to absolute capacitance may supplysuch information or resolve such issues.

In some embodiments, such transcapacitive sensing may be accomplished bymodulating one or more other electrodes near the button sensorelectrode. For example, in embodiments where a sensor device includes asensor electrode used for absolute capacitive sensing near one or moreother electrodes, changing the modulation of the other electrode(s) mayenable transcapacitive sensing between the other electrode(s) and thesensor electrode. Changing the modulation may involve switching from notmodulated to modulated, from modulated to not modulated, or from onemodulation to another modulation (e.g., from guarding to transmitting).Where the modulation of the other electrode(s) differ from the buttonsensor electrode, the other electrode(s) effectively transmits signalsto the button sensor electrode.

FIGS. 17A, 17B, 18A, 18B, 19A, 19B, 20A and 20B show a sensor device1705 with a round “button” sensor electrode 1710 surrounded by a sensorelectrode 1715. Cross sections BB′ and CC′, associated with FIGS. 17Aand 18A, respectively, help define the placement for input object 1725relative to an absolute capacitance sensing region 1730 and to inputsurface 1780. Referring now to 17A, during a first time period, buttonsensor electrode 1710 is modulated with respect to system ground (towhich the input object 1725 is assumed to be capacitively coupled).Sensor electrode 1715 may be held at a voltage substantially constantwith respect to system ground or modulated like button sensor electrode1710. When modulated like button sensor electrode 1710, sensor electrode1715 may provide an effective guard for button sensor electrode 1710.Substantially parallel field lines 1720 are generated that may interactwith input object 1725 in absolute capacitance sensing region 1730.Changes in the absolute capacitive coupling due to input object 1725 aredetected by “Sense” block 1735. There may be other guard or shieldelectrodes 1745 that are consistently driven by signals to help protectbutton sensor electrode 1710 from electrical noise such as, but notlimited to, system ground or various guard signals 1745.

Referring now to FIGS. 18A and 18B, it is shown that as input object1725 slides in towards absolute capacitance sensing region 1730, inputobject 1725 interacts with the substantially parallel field lines 1720even before it is in position to substantially affect field lines 1710.

Referring now to FIGS. 19A, 19B, 20A and 20B, during a second timeperiod, the button sensor electrode 1710 may be modulated in the sameway as has been described in conjunction with FIGS. 17A, 17B, 18A and18B during a first time period. For example, sensor electrode 1715 maybe modulated with respect to system ground (and differently from thebutton sensor electrode 1710). Cross sections DD′ and EE′, associatedwith FIGS. 19A and 20A, respectively, help define the placement forinput object 1725 relative to the transcapacitance sensing region 1955.Such a change in modulation of the sensor electrode 1715 enablestranscapacitive measurements in an annular region around button sensorelectrode 1710. Fringing field lines 1950 result and may be interceptedby an input object in transcapacitance sensing region 1955. Generally,the greatest amount of transcapacitive coupling may occur at thejunction between button sensor electrode 1710 and sensor electrodes1715. That is, the transcapacitive effect for such a configurationtypically asymptotes substantially and “maxes out” where input object1725 covers the entire junction. For many embodiments, this means thatthe junction is the region most transcapacitively sensitive to theinfluence of input object 1725. Changes in the transcapacitive couplingdue to the input object may be detected by “Sense” block/region 1935.Any other guard or shield electrodes present may be driven byappropriate guard/shield and modulated signals, 1945 and 1960,respectively, to help protect button sensor electrode 1710 fromelectrical noise.

Referring now to 20A and 20B, it is shown that as input object 1725slides in towards transcapacitance sensing region 1955, input object1725 interacts with fringing field lines 1950.

Transcapacitive readings thus may be used in combination with absolutecapacitance measurements obtained using button sensor electrode 1710 toprovide more information about the user input, such as types, sizes, andmotions of input objects. For example, combining such measurements mayenable differentiation of input objects moving toward the button sensorelectrode 1710 by sliding sideways versus descending from above.Similarly, combining such measurements may enable differentiation ofinput objects moving away from button sensor electrode 1710 by slidingoutwards versus lifting off. Below, a more detailed discussion follows.

For a system such as shown in FIGS. 17A and 17B, an absolute measurementgenerally does not enable disambiguation between an input objectdropping in toward button sensor electrode 1710 from above and an inputobject sliding in from the side to cover more of button sensor electrode1710. Having both absolute capacitance and transcapacitance measurementsenable this differentiation. For example, if the input object is afinger, and if the finger is dropping in on button sensor electrode 1710from above, changes in absolute and transcapacitive coupling largelychanges simultaneously. However, if the finger is sliding in from theside, changes in transcapacitance generally occur before changes inabsolute capacitance (since the finger interacts with area outside theedge of the button electrode before it interacts with the buttonelectrode).

Thus, it should be understood that comparing the transcapacitivecoupling reading to the absolute capacitive coupling reading may enabledetermination of extra information about the input. For example,determining size enables checking for input that is larger than inputobjects can be (e.g., part of a face such as a cheek, instead of afinger) and an appropriate response (e.g., rejection of the input)rather than activation.

For embodiments where absolute capacitance sensor electrodes are alreadynear other electrodes (e.g., electrodes used for shielding or for someother purpose), new physical electrodes to enable the transcapacitivesensing may not be added. One or more of these other electrodes may becontrolled separately with one or more different signals. For example, aguard electrode driven by a consistent guard signal 1745 may bemodulated differently in some time periods to provide transcapacitivesensing capability.

Where the plane electrode is modulated differently from button sensorelectrode 1710 and the input object, then the input object's effect maybe combined with the plane electrode's effect. In a simple case, thecombination can be additive. In more complex cases, the combination mayinvolve much more than superposition. This combination can be resolved,and absolute capacitance and transcapacitive components derived, if twoor more non-degenerate measurements are taken. Two measurements arenon-degenerate when they are not mathematical multiples of each other(e.g., the modulation amplitudes associated with the two measurementsare not just multiples or fractions of each other). For example,assuming other changes are insignificant, changing the modulation ofsensor electrode 1715 from being the same as button sensor electrode1710 to being different from button sensor electrode 1710 produces twonon-degenerate measurements.

Different modulations of a sensor electrode, such as sensor electrode1715, may be achieved in many ways. For example, a system can alternatebetween grounding sensor electrode 1715 in a first time period andmodulating sensor electrode 1715 within the sample bandwidth of sensorelectrode 1715 in a second time period. Output from sensor electrode1715 can be demodulated and averaged by device 1705 to provide anabsolute capacitance reading for the first time period and/or atranscapacitive reading for the second time period. The previous exampleinvolves switching between the voltage on sensor electrode 1715 frombeing substantially constant, with respect to system ground to onemodulated with respect to system ground. Some techniques foraccomplishing such modulation have been previously described inconjunction with FIG. 4. It should also be understood that two or moredifferent modulation signals may be used instead. Further, the signalsmay modulate electrical aspects other than voltage.

The absolute capacitance and transcapacitance measurements may be takenin any appropriate order, and over any appropriate periods of time. Forexample, the first time period may take place before or after the secondtime period. Some embodiments may take measurements of absolutecapacitance and transcapacitance in quick succession (quick relative tothe movement of the input device), and then demodulate them. Someembodiments may take multiple absolute capacitance measurements, thenmultiple transcapacitance measurements, and use averages or filteredversions of them. Some embodiments may take a first combination ofabsolute and transcapacitance measurements in a first time period, and asecond combination of absolute and transcapacitance measurements in asecond time period. Some embodiments may take alternating absolutecapacitance and transcapacitance measurements, and still use averages orfiltered versions of them. In many embodiments, all of this can beaccomplished within a reasonable touch time-span for sensing finger-typeinput and providing information to typical computer devices (e.g.,approximately 1/80 of a second).

In many embodiments for sensing human finger interactions, readings aretaken at 10 Hz or faster. Many embodiments take readings at tens ofhertz, hundreds of hertz, or thousands of hertz. Where the changes inmeasurements are expected to be slower (e.g., where distances to theinput object increases), the measurement sampling rate may be slower.Conversely, where the changes in measurements are expected to be faster(e.g., where distances to the input object is less), the measurementsampling rate may be faster. In many embodiments, the distance from thesensor electrodes to the input object is at least 1 mm, since at least 1mm of housing, cover layer, or other material separates the sensorelectrodes from the input object.

Many embodiments may include a proximity sensor configured to sense bothabsolute capacitance and transcapacitance. This proximity sensor may beconfigured to sense longer ranges (e.g., detect input objects relativelyfurther away). This proximity sensor may comprise a first sensorelectrode, a second sensor electrode, and a processing system coupled tothe first and second sensor electrode (arrangements shown and discussedin conjunction with FIG. 8, FIG. 10, FIG. 13, FIG. 15, and FIGS. 17-20may be configured to operate in a proximity sensing manner). Forpurposes of example, the method of operation below is described eithergenerically or with else briefly with respect to features of device 800of FIG. 8. However, it appreciated that this method of operating couldbe applied to any of the sensing devices described herein. In such adevice, the first and second sensor electrodes (e.g., 805 and 810) areconfigured to couple capacitively with an external object such. Aprocessing system (e.g., processing system 110B) of the device obtains afirst measurement indicative at least in part of the capacitancecoupling of the first sensor electrode with the external object and asecond measurement indicative at least in part of the capacitancecoupling of the first sensor electrode with the second sensor electrode.In one embodiment, the first and second measurements are not degenerate(e.g., the voltages applied for the first measurement are not allchanged by the same offset for the second measurement). This devicedetects a direct influence of the external object on the capacitivecoupling between the first and second sensor electrodes (e.g., byintercepting electric field lines that would have coupled the sensorelectrodes), and not an indirect influence of the external object movingthe first and second sensor electrodes together.

The first and second measurements may be taken by the processing systemin relatively close in time (e.g., such that changes in capacitivecoupling due to movement of the external object or other changes in theenvironment are negligible for the desired accuracy and resolution). Inmany embodiments, the processing system takes at least one of the firstand second measurements with the second sensor electrode acting as areceiving sensor electrode that is modulated relative to device/systemground. The processing system may also estimate, using at least thefirst and second measurements, at least one of a capacitive coupling thefirst and second sensor electrodes and a capacitive coupling between thesecond sensor electrode and the external object.

Referring now to FIG. 21, a conceptual diagram for a transcapacitiveimage integrated circuit 2100 is shown in accordance with embodiments ofthe present technology. FIG. 21 illustrates an embodiment of atranscapacitive mode of operation. As shown in FIG. 21, one transmitter2105 drives a row sensor electrode and multiple receivers can thendetect on multiple sensor electrode columns. In this configuration, eachreceiver channel 2110 senses mainly one transcapacitance 2115 betweenthe driven row and its own column.

Referring now to FIG. 22, a conceptual diagram for an absolute imageintegrated circuit 2200 is shown in accordance with embodiments of thepresent technology. FIG. 22 illustrates an absolute mode of operation inaccordance with embodiments of the present technology. As shown in FIG.22, multiple transmitters 2205 and 2210 drive on multiple individualrows and multiple receivers detect on multiple individual columns. Inthis configuration, each receiver channel 2215 senses mainly the totalcapacitance (capacitor 2225−capacitor 2220+capacitor 2230) between thedriven row and its own column. In FIG. 22, capacitance 2220 is the totaltranscapacitance of all in phase driving transmitters and capacitance2225 is the total transcapacitance of all non-driving transmitters. Thenon-driven transmitters may be held substantially to ground (or aconstant voltage). In other embodiments, the phase of some transmittersensor electrodes can be inverted.

Switching between absolute capacitance sensing mode and transcapacitivesensing mode is not limited to controlling when a touch sensor returnsto sleep or stays awake. Starting with an absolute capacitance sensingmode and switching to a transcapacitive sensing mode when certaincriteria have been met may be used in other applications. Examples ofother application include cases where an initial assessment of theenvironment proximate to the touch sensor, or an initial assessment oftouch sensor functionality, or the like is performed before fullimaging. In some embodiments, this approach is used where timeconstraints mean that there is not enough time to do a full image scan.

Capacitive Sensor Device—Example Circuitry

Referring now to FIG. 23, a capacitive sensor device 2300 is shown inaccordance with embodiments of the present technology. Capacitive sensordevice 2300 comprises: a transmitting assembly 2305, a receivingassembly 2320, a switching mechanism 2330, and a charge measurementmechanism 2335. Capacitive sensor device 2300 is configured for use withboth absolute and transcapacitive measurements.

As illustrated, transmitting assembly 2305 includes a plurality oftransmitting sensor electrodes 2310 and 2315 and receiving assembly 2320includes at least one receiving sensor electrode 2325. Switchingmechanism 2330 charges the receiving sensor electrodes (e.g., 2325) to acharged voltage. Charge measurement mechanism 2335 is, in oneembodiment, an operational amplifier 2350 that measures controls throughfeedback the charged voltage applied to the inverting input ofoperational amplifier 2350 by using a reference voltage Vref as an inputon the non-inverting input of operational amplifier 2350. It isappreciated that reference voltage Vref has a substantially constantvoltage. In one embodiment, capacitive sensor device 2300 furthercomprises a supply voltage, and reference voltage Vref is proportionalto the supply voltage.

In one embodiment, the plurality of transmitting sensor electrodes 2310and 2315 is coupled with at least two electric potentials Vdd and Vss,respectively, via a plurality of switches.

In one embodiment, switching mechanism 2330 comprises at least twoswitches 2346 and 2347. In one embodiment, switch 2346 couples thereceiving sensor electrode(s) (e.g., sensor electrode 2325) with a firstelectric potential Vdd during a first time period. In one embodiment,switch 2347 couples receiving sensor electrode(s) (e.g., sensorelectrode 2325) with charge measurement mechanism 2335 during a secondtime period. Furthermore, in one embodiment, a third switch (notillustrated) of switching mechanism 2330 can couple the receiving sensorelectrodes with a second electric potential.

In one embodiment, charge measurement mechanism 2335 of capacitivesensor device 2300, includes: amplifier 2350, a reset 2355, and anintegrating feedback capacitance 2360. Feedback capacitance 2360 iscoupled with amplifier 2350 and accumulates charge relative to referencevoltage Vref. Charge measurement mechanism 2335 uses amplifier 2350 tocontrol a charge on integrating feedback capacitance 2360 based at leastin part on reference voltage Vref, which is coupled with thenon-inverting input of amplifier 2350. Reset 2355 may comprise resistoror a switch (illustrated). In some embodiments the Reset 2355 may be apartial reset or other appropriate methods. In other embodiments,feedback capacitance 2360 may comprise multiple separately inverted(e.g., switched) capacitances.

In one embodiment, a first set of the plurality of transmitting sensorelectrodes (2310 and 2315) are used to emit a guard signal. A variety ofguard signals have been discussed herein and reference is made at leastto the discussion of guard signals that appears in conjunction with FIG.4. In particular the modulation of transmitting sensor electrodes 2310and 2315 may serve to minimize the required charge transfer throughfeedback capacitance 2360. Furthermore, capacitive sensor device 2300comprises a capacitive coupling component that performs at least two ofthe following: 1) capacitively couple at least one receiving sensorelectrode and an input object, where the at least one receiving sensorelectrode (e.g., receiving sensor electrode 2325) is modulated withrespect to system ground while concurrently at least one transmittingsensor electrode of the plurality of transmitting sensor electrodes 2310and 2315 electrically guards the at least one receiving sensor electrode2325; 2) capacitively couple at least one transmitting sensor electrode(2310 or 2315) and the at least one receiving sensor electrode 2325,where the at least one transmitting sensor electrode (2310 or 2315) ismodulated with respect to the at least one receiving sensor electrode2325 while concurrently the receiving sensor electrode 2325 is not beingmodulated; 3) capacitively couple the at least one receiving sensorelectrode 2325 and the input object and capacitively couple the at leastone receiving sensor electrode 2325 and the at least one transmittingsensor electrode of the plurality of transmitting sensor electrodes 2310and 2315, where the at least one receiving sensor electrode 2325 ismodulated in a first way with respect to the system ground whileconcurrently the at least one transmitting sensor electrode of theplurality of transmitting sensor electrodes 2310 and 2315 is beingmodulated with respect to the at least one receiving electrode 2325 in afirst way; and 4) capacitively couple the at least one receiving sensorelectrode 2325 and the input object and capacitively couple the at leastone receiving sensor electrode 2325 and the at least one transmittingsensor electrode of the plurality of transmitting sensor electrodes 2310and 2315, where the at least one receiving sensor electrode 2325 ismodulated with respect to the system ground while concurrently the atleast one transmitting sensor electrode of the plurality of transmittingsensor electrodes 2310 and 2315 is modulated with respect to the atleast one receiving sensor electrode 2325 in a second way.

Furthermore, in one embodiment, the at least one transmitting sensorelectrode of the plurality of transmitting sensor electrodes 2310 and2315 electrically guards the at least one receiving sensor electrode2325. For example, at least one transmitting sensor electrode of theplurality of transmitting sensor electrodes 2310 and 2315 is driven witha constant voltage potential and one or more transmitting sensorelectrodes of the plurality of transmitting sensor electrodes 2310 and2315 other than the at least one transmitting sensor electrode isalternately driven between two electric potentials.

Moreover, in one embodiment, the at least one receiving sensor electrode2325 is modulated with respect to the system ground while concurrentlythe at least one transmitting sensor electrode of the plurality oftransmitting sensor electrodes 2310 and 2315 is being modulated withrespect to the at least one receiving electrode 2325 in a first way thatcomprises at least one of the following: 1) the at least onetransmitting sensor electrode of the plurality of transmitting sensorelectrodes 2310 and 2315 is driven in an opposite polarity to the atleast one receiving sensor electrode 2325; and 2) the at least onetransmitting sensor electrode of the plurality of transmitting sensorelectrodes 2310 and 2315 and the at least one receiving sensor electrode2325 is driven with different amplitudes.

In one embodiment, the at least one receiving sensor electrode 2325 ismodulated with respect to the system ground while concurrently the atleast one transmitting sensor electrode of the plurality of transmittingsensor electrodes 2310 and 2315 is being modulated with respect to theat least one receiving electrode 2325 in a second way comprises at leastone of the following: 1) the at least one transmitting sensor electrodeof the plurality of transmitting sensor electrodes 2310 and 2315 isdriven in an opposite polarity to the at least one receiving sensorelectrode 2325; and 2) the at least one transmitting sensor electrode ofthe plurality of transmitting sensor electrodes 2310 and 2315 and the atleast one receiving sensor electrode 2325 are driven with differentamplitudes.

In one embodiment, the at least one receiving sensor electrode 2325comprises two sensor electrodes: a first receiving sensor electrode anda second receiving sensor electrode, where the input switch 2347 is amultiplexer configured for allowing the first receiving sensor electrodeand the second sensor electrode to be coupled in turn with chargemeasurement mechanism 2335.

Referring still to FIG. 23, in one embodiment, capacitive sensing device2300 comprises a transmitting assembly 2305 that includes a plurality oftransmitting sensor electrodes that are coupled with at least twoelectric potentials (e.g., Vdd and Vss), respectively, via a pluralityof switches. Capacitive sensing device 2300 further comprises areceiving assembly 2320 that includes at least one receiving sensorelectrode 2325; a switching mechanism 2330 that charges the at least onereceiving sensor electrode to a charged voltage; and a chargemeasurement mechanism that controls the charged voltage applied to aninput of an amplifier 2350 of the charge measurement mechanism byfeedback on a substantially constant reference voltage Vref. Vref may beproportional to a supply voltage. In one such embodiment, chargemeasurement mechanism 2335 comprises an amplifier 2350; a reset 2355;and an integrating feedback capacitance 2360. The integrating feedbackcapacitance 2360 is coupled with the amplifier 2350 and acts toaccumulate charge relative to reference voltage Vref. Charge measurementmechanism 2335 uses amplifier 2350 to control a charge on integratingfeedback capacitance 2360 based at least in part on the referencevoltage Vref. Reset 2355 may comprise resistor or a switch(illustrated). Capacitive sensor device 2300 can be used, in accordancewith the techniques described herein for both absolute andtranscapacitive measurements.

In one embodiment, switching mechanism 2330 comprises at least twoswitches 2346 and 2347. A first switch 2346 couples the at least onereceiving sensor electrode 2325 with a first electric potential during afirst time period and a second switch couples the at least one receivingsensor electrode 2325 with charge measurement mechanism 2335 during asecond time period. Furthermore, a third switch (not illustrated) ofswitching mechanism 2330 couples the at least one receiver sensorelectrode 2325 with a second electric potential.

What is claimed is:
 1. A capacitive sensor device comprising: a firstplurality of sensor electrodes; a second plurality of sensor electrodes;and a processing system coupled to the first plurality of sensorelectrodes and the second plurality of sensor electrodes, the processingsystem configured to: acquire a first plurality of absolute capacitivemeasurements by emitting first electrical signals from a first set ofthe first plurality of sensor electrodes and receiving first resultingelectrical signals with the first set of the first plurality of sensorelectrodes, the first resulting electrical signals resulting from thefirst electrical signals emitted from the first set of the firstplurality of sensor electrodes, wherein the first plurality of absolutecapacitive measurements comprise measurements of self-capacitance of thefirst plurality of sensor electrodes with respect to system ground, andacquire a second plurality of transcapacitive measurements by emittingsecond electrical signals from a first set of the second plurality ofsensor electrodes and receiving second resulting electrical signals witha second set of the first plurality of sensor electrodes, the secondresulting electrical signals resulting from the second electricalsignals emitted from the first set of the second plurality of sensorelectrodes, wherein the second plurality of transcapacitive measurementscomprise measurements of mutual capacitance between the first set of thesecond plurality of sensor electrodes and the second set of the firstplurality of sensor electrodes, wherein the first set of the firstplurality of sensor electrodes and the second set of the first pluralityof sensor electrodes have at least one sensor electrode in common, andwherein the at least one sensor electrode in common concurrentlyreceives the first resulting electrical signals and the second resultingelectrical signals.
 2. The capacitive sensor device of claim 1, whereinthe processing system is configured to acquire the first plurality ofabsolute capacitive measurements and the second plurality oftranscapacitive measurements simultaneously.
 3. The capacitive sensordevice of claim 1, wherein the processing system is further configuredto: determine, using the first plurality of absolute capacitivemeasurements, which sensor electrodes correspond to the second set ofthe first plurality of sensor electrodes.
 4. The capacitive sensordevice of claim 1, wherein the processing system is further configuredto: determine a first position estimate of an input object using thefirst plurality of absolute capacitive measurements, and determine asecond position estimate of the input object using the second pluralityof transcapacitive measurements, wherein the second position estimatecorresponds to a location of the input object that is relatively closerto an input surface than the first position estimate.
 5. The capacitivesensor device of claim 1, wherein the processing system is furtherconfigured to: determine, using the first plurality of absolutecapacitive measurements and the second plurality of transcapacitivemeasurements, at least one of a size of an input object, a type of theinput object, and a capacitive coupling to system ground of the inputobject.
 6. The capacitive sensor device of claim 1, wherein the firstplurality of sensor electrodes is aligned along a first axis and thesecond plurality of sensor electrodes are aligned along a second axisnon-parallel to the first axis.
 7. A method of capacitive sensingcomprising: emitting first electrical signals from a first set of afirst plurality of sensor electrodes; receiving, with a second set ofthe first plurality of sensor electrodes, first resulting electricalsignals to acquire a first plurality of absolute capacitive measurementswherein the first resulting electrical signals result from the firstelectrical signals being emitted from the first set of the firstplurality of sensor electrodes, and wherein the first plurality ofabsolute capacitive measurements comprises measurements ofself-capacitance of the first plurality of sensor electrodes withrespect to system ground; emitting second electrical signals from afirst set of a second plurality of sensor electrodes; and receiving,with a second set of the first plurality of sensor electrodes, secondresulting electrical signals to acquire a second plurality oftranscapacitive measurements, wherein the second resulting electricalsignals resulting from the second electrical signals being emitted fromthe first set of the second plurality of sensor electrodes, wherein thesecond plurality of transcapacitive measurements comprise measurementsof mutual capacitance between the first set of the second plurality ofsensor electrodes and the second set of the first plurality of sensorelectrodes, wherein the first set of the first plurality of sensorelectrodes and the second set of the first plurality of sensorelectrodes have at least one sensor electrode in common and wherein theat least one sensor electrode in common concurrently receives the firstresulting electrical signals and the second resulting electricalsignals.
 8. The method of claim 7, wherein emitting the first electricalsignals and emitting the second electrical signals occur simultaneously.9. The method of claim 7, further comprising: determining, using thefirst plurality of absolute capacitive measurements, which sensorelectrodes correspond to the second set of the first plurality of sensorelectrodes.
 10. The method of claim 7, further comprising: determining afirst position estimate of an input object using the first plurality ofabsolute capacitive measurements, and determining a second positionestimate of the input object using the second plurality oftranscapacitive measurements, wherein the second position estimatecorresponds to a location of the input object that is relatively closerto an input surface than the first position estimate.
 11. The method ofclaim 7, further comprising: determining, using the first plurality ofabsolute capacitive measurements and the second plurality oftranscapacitive measurements, at least one of a size of an input object,a type of the input object, and a capacitive coupling to system groundof the input object.
 12. A device for capacitive sensing, the devicecomprising: a processing system configured to couple to a firstplurality of sensor electrodes and a second plurality of sensorelectrodes, the processing system comprising circuitry and logicconfigured to: acquire a first plurality of absolute capacitivemeasurements by emitting first electrical signals from a first set ofthe first plurality of sensor electrodes and receiving first resultingelectrical signals with the first set of the first plurality of sensorelectrodes, the first resulting electrical signals resulting from thefirst electrical signals emitted from the first set of the firstplurality of sensor electrodes, wherein the first plurality of absolutecapacitive measurements comprise measurements of self-capacitance of thefirst plurality of sensor electrodes with respect to system ground, andacquire a second plurality of transcapacitive measurements by emittingsecond electrical signals from a first set of the second plurality ofsensor electrodes and receiving second resulting electrical signals witha second set of the first plurality of sensor electrodes, the secondresulting electrical signals resulting from the second electricalsignals emitted from the first set of the second plurality of sensorelectrodes, wherein the second plurality of transcapacitive measurementscomprise measurements of mutual capacitance between the first set of thesecond plurality of sensor electrodes and the second set of the firstplurality of sensor electrodes, wherein the first set of the firstplurality of sensor electrodes and the second set of the first pluralityof sensor electrodes have at least one sensor electrode in common, andwherein the at least one sensor electrode in common concurrentlyreceives the first resulting electrical signals and the second resultingelectrical signals.
 13. The device of claim 12, wherein the processingsystem is configured to acquire the first plurality of absolutecapacitive measurements and the second plurality of transcapacitivemeasurements simultaneously.
 14. The device of claim 12, wherein theprocessing system is further configured to: determine the second set ofthe first plurality of sensor electrodes using the first plurality ofabsolute capacitive measurements.
 15. The device of claim 12, whereinthe processing system is further configured to: determine a firstposition estimate of an input object using the first plurality ofabsolute capacitive measurements, and determine a second positionestimate of the input object using the second plurality oftranscapacitive measurements, wherein the second position estimatecorresponds to a location of the input object that is relatively closerto an input surface than the first position estimate.
 16. The device ofclaim 12, wherein the processing system is further configured to:determine, using the first plurality of absolute capacitive measurementsand the second plurality of transcapacitive measurements, at least oneof a size of an input object, a type of the input object, and acapacitive coupling to system ground of the input object.
 17. Acapacitive sensor device comprising: a plurality of transmitting sensorelectrodes; a plurality of receiving sensor electrodes; and a processingsystem coupled to the plurality of transmitting sensor electrodes andthe plurality of receiving sensor electrodes, the processing systemconfigured to: acquire a first plurality of absolute capacitivemeasurements by emitting first electrical signals from a first set of afirst plurality of transmitting sensor electrodes and receiving firstresulting electrical signals with a first set of a first plurality ofreceiving sensor electrodes, the first resulting electrical signalsresulting from the first electrical signals emitted from the first setof the first plurality of transmitting sensor electrodes, wherein thefirst plurality of absolute capacitive measurements comprisemeasurements of self-capacitance of the first plurality of receivingsensor electrodes with respect to system ground, and acquire a secondplurality of transcapacitive measurements by emitting second electricalsignals from a first set of a second plurality of transmitting sensorelectrodes and receiving second resulting electrical signals with asecond set of a first plurality of receiving sensor electrodes, thesecond resulting electrical signals resulting from the second electricalsignals emitted from the first set of the second plurality oftransmitting sensor electrodes, wherein the second plurality oftranscapacitive measurements comprise measurements of mutual capacitancebetween the first set of the second plurality of transmitting sensorelectrodes and the second set of the first plurality of receiving sensorelectrodes, wherein the first set of the first plurality of transmittingsensor electrodes and the second set of the first plurality of receivingsensor electrodes have at least one sensor electrode in common, andwherein the at least one sensor electrode in common concurrentlyreceives the first resulting electrical signals and the second resultingelectrical signals.
 18. The capacitive sensor device of claim 17,wherein the processing system is further configured to: detect firstinput using the transcapacitive measurements; and detect second inputusing the absolute capacitive measurements, wherein the second inputcorresponds to a location that is relatively farther away from an inputsurface than the first input.
 19. A processing system for capacitivesensing, the processing system comprising: circuitry and logicconfigured to: acquire a first plurality of absolute capacitivemeasurements by emitting first electrical signals from a first set of afirst plurality of sensor electrodes and receiving first resultingelectrical signals with the first set of the first plurality of sensorelectrodes, the first resulting electrical signals resulting from thefirst electrical signals emitted from the first set of the firstplurality of sensor electrodes, wherein the first plurality of absolutecapacitive measurements comprise measurements of self-capacitance of thefirst plurality of sensor electrodes with respect to system ground, andacquire a second plurality of transcapacitive measurements by emittingsecond electrical signals from a first set of a second plurality ofsensor electrodes and receiving second resulting electrical signals witha second set of the first plurality of sensor electrodes, the secondresulting electrical signals resulting from the second electricalsignals emitted from the first set of the second plurality of sensorelectrodes, wherein the second plurality of transcapacitive measurementscomprise measurements of mutual capacitance between the first set of thesecond plurality of sensor electrodes and the second set of the firstplurality of sensor electrodes, wherein the first set of the firstplurality of sensor electrodes and the second set of the first pluralityof sensor electrodes have at least one sensor electrode in common, andwherein the at least one sensor electrode in common concurrentlyreceives the first resulting electrical signals and the second resultingelectrical signals.
 20. The processing system of claim 19, wherein thecircuitry and logic are further configured to: detect a first inputusing the transcapacitive measurements; and detect a second input usingthe absolute capacitive measurements, wherein the second inputcorresponds to a location that is relatively farther away from an inputsurface than the first input.